After a decade or extra the place Single-Web page-Functions generated by
JavaScript frameworks have
turn out to be the norm, we see that server-side rendered HTML is turning into
fashionable once more, additionally because of libraries corresponding to HTMX or Turbo. Writing a wealthy internet UI in a
historically server-side language like Go or Java is no longer simply doable,
however a really enticing proposition.
We then face the issue of the best way to write automated exams for the HTML
components of our internet functions. Whereas the JavaScript world has advanced highly effective and refined methods to check the UI,
ranging in measurement from unit-level to integration to end-to-end, in different
languages we would not have such a richness of instruments obtainable.
When writing an internet utility in Go or Java, HTML is often generated
via templates, which include small fragments of logic. It’s actually
doable to check them not directly via end-to-end exams, however these exams
are gradual and costly.
We are able to as an alternative write unit exams that use CSS selectors to probe the
presence and proper content material of particular HTML components inside a doc.
Parameterizing these exams makes it straightforward so as to add new exams and to obviously
point out what particulars every check is verifying. This strategy works with any
language that has entry to an HTML parsing library that helps CSS
selectors; examples are offered in Go and Java.
Degree 1: checking for sound HTML
The primary factor we wish to examine is that the HTML we produce is
mainly sound. I do not imply to examine that HTML is legitimate based on the
W3C; it could be cool to do it, however it’s higher to begin with a lot less complicated and sooner checks.
For example, we would like our exams to
break if the template generates one thing like
<div>foo</p>
Let’s examine the best way to do it in phases: we begin with the next check that
tries to compile the template. In Go we use the usual html/template package deal.
Go
func Test_wellFormedHtml(t *testing.T) {
templ := template.Should(template.ParseFiles("index.tmpl"))
_ = templ
}
In Java, we use jmustache
as a result of it is quite simple to make use of; Freemarker or
Velocity are different frequent selections.
Java
@Check
void indexIsSoundHtml() {
var template = Mustache.compiler().compile(
new InputStreamReader(
getClass().getResourceAsStream("/index.tmpl")));
}
If we run this check, it’ll fail, as a result of the index.tmpl file does
not exist. So we create it, with the above damaged HTML. Now the check ought to go.
Then we create a mannequin for the template to make use of. The applying manages a todo-list, and
we will create a minimal mannequin for demonstration functions.
Go
func Test_wellFormedHtml(t *testing.T) {
templ := template.Should(template.ParseFiles("index.tmpl"))
mannequin := todo.NewList()
_ = templ
_ = mannequin
}
Java
@Check
void indexIsSoundHtml() {
var template = Mustache.compiler().compile(
new InputStreamReader(
getClass().getResourceAsStream("/index.tmpl")));
var mannequin = new TodoList();
}
Now we render the template, saving the ends in a bytes buffer (Go) or as a String (Java).
Go
func Test_wellFormedHtml(t *testing.T) {
templ := template.Should(template.ParseFiles("index.tmpl"))
mannequin := todo.NewList()
var buf bytes.Buffer
err := templ.Execute(&buf, mannequin)
if err != nil {
panic(err)
}
}
Java
@Check
void indexIsSoundHtml() {
var template = Mustache.compiler().compile(
new InputStreamReader(
getClass().getResourceAsStream("/index.tmpl")));
var mannequin = new TodoList();
var html = template.execute(mannequin);
}
At this level, we wish to parse the HTML and we count on to see an
error, as a result of in our damaged HTML there’s a div ingredient that
is closed by a p ingredient. There’s an HTML parser within the Go
customary library, however it’s too lenient: if we run it on our damaged HTML, we do not get an
error. Fortunately, the Go customary library additionally has an XML parser that may be
configured to parse HTML (because of this Stack Overflow reply)
Go
func Test_wellFormedHtml(t *testing.T) {
templ := template.Should(template.ParseFiles("index.tmpl"))
mannequin := todo.NewList()
// render the template right into a buffer
var buf bytes.Buffer
err := templ.Execute(&buf, mannequin)
if err != nil {
panic(err)
}
// examine that the template could be parsed as (lenient) XML
decoder := xml.NewDecoder(bytes.NewReader(buf.Bytes()))
decoder.Strict = false
decoder.AutoClose = xml.HTMLAutoClose
decoder.Entity = xml.HTMLEntity
for {
_, err := decoder.Token()
swap err {
case io.EOF:
return // We're executed, it is legitimate!
case nil:
// do nothing
default:
t.Fatalf("Error parsing html: %s", err)
}
}
}
This code configures the HTML parser to have the fitting stage of leniency
for HTML, after which parses the HTML token by token. Certainly, we see the error
message we needed:
--- FAIL: Test_wellFormedHtml (0.00s)
index_template_test.go:61: Error parsing html: XML syntax error on line 4: sudden finish ingredient </p>
In Java, a flexible library to make use of is jsoup:
Java
@Check
void indexIsSoundHtml() {
var template = Mustache.compiler().compile(
new InputStreamReader(
getClass().getResourceAsStream("/index.tmpl")));
var mannequin = new TodoList();
var html = template.execute(mannequin);
var parser = Parser.htmlParser().setTrackErrors(10);
Jsoup.parse(html, "", parser);
assertThat(parser.getErrors()).isEmpty();
}
And we see it fail:
java.lang.AssertionError: Anticipating empty however was:<[<1:13>: Unexpected EndTag token [</p>] when in state [InBody],
Success! Now if we copy over the contents of the TodoMVC
template to our index.tmpl file, the check passes.
The check, nevertheless, is simply too verbose: we extract two helper features, in
order to make the intention of the check clearer, and we get
Go
func Test_wellFormedHtml(t *testing.T) {
mannequin := todo.NewList()
buf := renderTemplate("index.tmpl", mannequin)
assertWellFormedHtml(t, buf)
}
Java
@Check
void indexIsSoundHtml() {
var mannequin = new TodoList();
var html = renderTemplate("/index.tmpl", mannequin);
assertSoundHtml(html);
}
Degree 2: testing HTML construction
What else ought to we check?
We all know that the seems to be of a web page can solely be examined, in the end, by a
human how it’s rendered in a browser. Nevertheless, there’s typically
logic in templates, and we would like to have the ability to check that logic.
One is perhaps tempted to check the rendered HTML with string equality,
however this system fails in apply, as a result of templates include numerous
particulars that make string equality assertions impractical. The assertions
turn out to be very verbose, and when studying the assertion, it turns into tough
to grasp what it’s that we’re making an attempt to show.
What we want
is a method to claim that some components of the rendered HTML
correspond to what we count on, and to ignore all the small print we do not
care about. A method to do that is by working queries with the CSS selector language:
it’s a highly effective language that permits us to pick out the
components that we care about from the entire HTML doc. As soon as we have now
chosen these components, we (1) rely that the variety of ingredient returned
is what we count on, and (2) that they include the textual content or different content material
that we count on.
The UI that we’re presupposed to generate seems to be like this:
There are a number of particulars which can be rendered dynamically:
- The variety of gadgets and their textual content content material change, clearly
- The type of the todo-item adjustments when it is accomplished (e.g., the
second) - The “2 gadgets left” textual content will change with the variety of non-completed
gadgets - One of many three buttons “All”, “Lively”, “Accomplished” will probably be
highlighted, relying on the present url; as an illustration if we determine that the
url that reveals solely the “Lively” gadgets is/lively, then when the present url
is/lively, the “Lively” button ought to be surrounded by a skinny pink
rectangle - The “Clear accomplished” button ought to solely be seen if any merchandise is
accomplished
Every of this issues could be examined with the assistance of CSS selectors.
This can be a snippet from the TodoMVC template (barely simplified). I
haven’t but added the dynamic bits, so what we see right here is static
content material, offered for example:
index.tmpl
<part class="todoapp">
<ul class="todo-list">
<!-- These are right here simply to point out the construction of the checklist gadgets -->
<!-- Listing gadgets ought to get the category `accomplished` when marked as accomplished -->
<li class="accomplished"> ②
<div class="view">
<enter class="toggle" kind="checkbox" checked>
<label>Style JavaScript</label> ①
<button class="destroy"></button>
</div>
</li>
<li>
<div class="view">
<enter class="toggle" kind="checkbox">
<label>Purchase a unicorn</label> ①
<button class="destroy"></button>
</div>
</li>
</ul>
<footer class="footer">
<!-- This ought to be `0 gadgets left` by default -->
<span class="todo-count"><sturdy>0</sturdy> merchandise left</span> ⓷
<ul class="filters">
<li>
<a class="chosen" href="#/">All</a> ④
</li>
<li>
<a href="#/lively">Lively</a>
</li>
<li>
<a href="#/accomplished">Accomplished</a>
</li>
</ul>
<!-- Hidden if no accomplished gadgets are left ↓ -->
<button class="clear-completed">Clear accomplished</button> ⑤
</footer>
</part>
By trying on the static model of the template, we will deduce which
CSS selectors can be utilized to establish the related components for the 5 dynamic
options listed above:
| characteristic | CSS selector | |
|---|---|---|
| ① | All of the gadgets | ul.todo-list li |
| ② | Accomplished gadgets | ul.todo-list li.accomplished |
| ⓷ | Objects left | span.todo-count |
| ④ | Highlighted navigation hyperlink | ul.filters a.chosen |
| ⑤ | Clear accomplished button | button.clear-completed |
We are able to use these selectors to focus our exams on simply the issues we wish to check.
Testing HTML content material
The primary check will search for all of the gadgets, and show that the information
arrange by the check is rendered accurately.
func Test_todoItemsAreShown(t *testing.T) {
mannequin := todo.NewList()
mannequin.Add("Foo")
mannequin.Add("Bar")
buf := renderTemplate(mannequin)
// assert there are two <li> components contained in the <ul class="todo-list">
// assert the primary <li> textual content is "Foo"
// assert the second <li> textual content is "Bar"
}
We’d like a option to question the HTML doc with our CSS selector; a great
library for Go is goquery, that implements an API impressed by jQuery.
In Java, we maintain utilizing the identical library we used to check for sound HTML, specifically
jsoup. Our check turns into:
Go
func Test_todoItemsAreShown(t *testing.T) {
mannequin := todo.NewList()
mannequin.Add("Foo")
mannequin.Add("Bar")
buf := renderTemplate("index.tmpl", mannequin)
// parse the HTML with goquery
doc, err := goquery.NewDocumentFromReader(bytes.NewReader(buf.Bytes()))
if err != nil {
// if parsing fails, we cease the check right here with t.FatalF
t.Fatalf("Error rendering template %s", err)
}
// assert there are two <li> components contained in the <ul class="todo-list">
choice := doc.Discover("ul.todo-list li")
assert.Equal(t, 2, choice.Size())
// assert the primary <li> textual content is "Foo"
assert.Equal(t, "Foo", textual content(choice.Nodes[0]))
// assert the second <li> textual content is "Bar"
assert.Equal(t, "Bar", textual content(choice.Nodes[1]))
}
func textual content(node *html.Node) string {
// A bit of mess resulting from the truth that goquery has
// a .Textual content() methodology on Choice however not on html.Node
sel := goquery.Choice{Nodes: []*html.Node{node}}
return strings.TrimSpace(sel.Textual content())
}
Java
@Check
void todoItemsAreShown() throws IOException {
var mannequin = new TodoList();
mannequin.add("Foo");
mannequin.add("Bar");
var html = renderTemplate("/index.tmpl", mannequin);
// parse the HTML with jsoup
Doc doc = Jsoup.parse(html, "");
// assert there are two <li> components contained in the <ul class="todo-list">
var choice = doc.choose("ul.todo-list li");
assertThat(choice).hasSize(2);
// assert the primary <li> textual content is "Foo"
assertThat(choice.get(0).textual content()).isEqualTo("Foo");
// assert the second <li> textual content is "Bar"
assertThat(choice.get(1).textual content()).isEqualTo("Bar");
}
If we nonetheless have not modified the template to populate the checklist from the
mannequin, this check will fail, as a result of the static template
todo gadgets have completely different textual content:
Go
--- FAIL: Test_todoItemsAreShown (0.00s)
index_template_test.go:44: First checklist merchandise: need Foo, obtained Style JavaScript
index_template_test.go:49: Second checklist merchandise: need Bar, obtained Purchase a unicorn
Java
IndexTemplateTest > todoItemsAreShown() FAILED
org.opentest4j.AssertionFailedError:
Anticipating:
<"Style JavaScript">
to be equal to:
<"Foo">
however was not.
We repair it by making the template use the mannequin information:
Go
<ul class="todo-list"> {{ vary .Objects }} <li> <div class="view"> <enter class="toggle" kind="checkbox"> <label>{{ .Title }}</label> <button class="destroy"></button> </div> </li> {{ finish }} </ul>
Java – jmustache
<ul class="todo-list"> {{ #allItems }} <li> <div class="view"> <enter class="toggle" kind="checkbox"> <label>{{ title }}</label> <button class="destroy"></button> </div> </li> {{ /allItems }} </ul>
Check each content material and soundness on the identical time
Our check works, however it’s a bit verbose, particularly the Go model. If we will have extra
exams, they’ll turn out to be repetitive and tough to learn, so we make it extra concise by extracting a helper perform for parsing the html. We additionally take away the
feedback, because the code ought to be clear sufficient
Go
func Test_todoItemsAreShown(t *testing.T) {
mannequin := todo.NewList()
mannequin.Add("Foo")
mannequin.Add("Bar")
buf := renderTemplate("index.tmpl", mannequin)
doc := parseHtml(t, buf)
choice := doc.Discover("ul.todo-list li")
assert.Equal(t, 2, choice.Size())
assert.Equal(t, "Foo", textual content(choice.Nodes[0]))
assert.Equal(t, "Bar", textual content(choice.Nodes[1]))
}
func parseHtml(t *testing.T, buf bytes.Buffer) *goquery.Doc {
doc, err := goquery.NewDocumentFromReader(bytes.NewReader(buf.Bytes()))
if err != nil {
// if parsing fails, we cease the check right here with t.FatalF
t.Fatalf("Error rendering template %s", err)
}
return doc
}
Java
@Check
void todoItemsAreShown() throws IOException {
var mannequin = new TodoList();
mannequin.add("Foo");
mannequin.add("Bar");
var html = renderTemplate("/index.tmpl", mannequin);
var doc = parseHtml(html);
var choice = doc.choose("ul.todo-list li");
assertThat(choice).hasSize(2);
assertThat(choice.get(0).textual content()).isEqualTo("Foo");
assertThat(choice.get(1).textual content()).isEqualTo("Bar");
}
non-public static Doc parseHtml(String html) {
return Jsoup.parse(html, "");
}
A lot better! Not less than for my part. Now that we extracted the parseHtml helper, it is
a good suggestion to examine for sound HTML within the helper:
Go
func parseHtml(t *testing.T, buf bytes.Buffer) *goquery.Doc {
assertWellFormedHtml(t, buf)
doc, err := goquery.NewDocumentFromReader(bytes.NewReader(buf.Bytes()))
if err != nil {
// if parsing fails, we cease the check right here with t.FatalF
t.Fatalf("Error rendering template %s", err)
}
return doc
}
Java
non-public static Doc parseHtml(String html) {
var parser = Parser.htmlParser().setTrackErrors(10);
var doc = Jsoup.parse(html, "", parser);
assertThat(parser.getErrors()).isEmpty();
return doc;
}
And with this, we will eliminate the primary check that we wrote, as we at the moment are testing for sound HTML on a regular basis.
The second check
Now we’re in a great place for testing extra rendering logic. The
second dynamic characteristic in our checklist is “Listing gadgets ought to get the category
accomplished when marked as accomplished”. We are able to write a check for this:
Go
func Test_completedItemsGetCompletedClass(t *testing.T) {
mannequin := todo.NewList()
mannequin.Add("Foo")
mannequin.AddCompleted("Bar")
buf := renderTemplate("index.tmpl", mannequin)
doc := parseHtml(t, buf)
choice := doc.Discover("ul.todo-list li.accomplished")
assert.Equal(t, 1, choice.Dimension())
assert.Equal(t, "Bar", textual content(choice.Nodes[0]))
}
Java
@Check
void completedItemsGetCompletedClass() {
var mannequin = new TodoList();
mannequin.add("Foo");
mannequin.addCompleted("Bar");
var html = renderTemplate("/index.tmpl", mannequin);
Doc doc = Jsoup.parse(html, "");
var choice = doc.choose("ul.todo-list li.accomplished");
assertThat(choice).hasSize(1);
assertThat(choice.textual content()).isEqualTo("Bar");
}
And this check could be made inexperienced by including this little bit of logic to the
template:
Go
<ul class="todo-list">
{{ vary .Objects }}
<li class="{{ if .IsCompleted }}accomplished{{ finish }}">
<div class="view">
<enter class="toggle" kind="checkbox">
<label>{{ .Title }}</label>
<button class="destroy"></button>
</div>
</li>
{{ finish }}
</ul>
Java – jmustache
<ul class="todo-list">
{{ #allItems }}
<li class="{{ #isCompleted }}accomplished{{ /isCompleted }}">
<div class="view">
<enter class="toggle" kind="checkbox">
<label>{{ title }}</label>
<button class="destroy"></button>
</div>
</li>
{{ /allItems }}
</ul>
So little by little, we will check and add the assorted dynamic options
that our template ought to have.
Make it straightforward so as to add new exams
The primary of the 20 suggestions from the wonderful speak by Russ Cox on Go
Testing is “Make it straightforward so as to add new check circumstances“. Certainly, in Go there
is a bent to make most exams parameterized, for this very cause.
However, whereas Java has
good assist
for parameterized exams with JUnit 5, they are not used as a lot.
Since our present two exams have the identical construction, we
may issue them right into a single parameterized check.
A check case for us will encompass:
- A reputation (in order that we will produce clear error messages when the check
fails) - A mannequin (in our case a
todo.Listing) - A CSS selector
- A listing of textual content matches that we look forward to finding once we run the CSS
selector on the rendered HTML.
So that is the information construction for our check circumstances:
Go
var testCases = []struct {
identify string
mannequin *todo.Listing
selector string
matches []string
}{
{
identify: "all todo gadgets are proven",
mannequin: todo.NewList().
Add("Foo").
Add("Bar"),
selector: "ul.todo-list li",
matches: []string{"Foo", "Bar"},
},
{
identify: "accomplished gadgets get the 'accomplished' class",
mannequin: todo.NewList().
Add("Foo").
AddCompleted("Bar"),
selector: "ul.todo-list li.accomplished",
matches: []string{"Bar"},
},
}
Java
document TestCase(String identify,
TodoList mannequin,
String selector,
Listing<String> matches) {
@Override
public String toString() {
return identify;
}
}
public static TestCase[] indexTestCases() {
return new TestCase[]{
new TestCase(
"all todo gadgets are proven",
new TodoList()
.add("Foo")
.add("Bar"),
"ul.todo-list li",
Listing.of("Foo", "Bar")),
new TestCase(
"accomplished gadgets get the 'accomplished' class",
new TodoList()
.add("Foo")
.addCompleted("Bar"),
"ul.todo-list li.accomplished",
Listing.of("Bar")),
};
}
And that is our parameterized check:
Go
func Test_indexTemplate(t *testing.T) {
for _, check := vary testCases {
t.Run(check.identify, func(t *testing.T) {
buf := renderTemplate("index.tmpl", check.mannequin)
assertWellFormedHtml(t, buf)
doc := parseHtml(t, buf)
choice := doc.Discover(check.selector)
require.Equal(t, len(check.matches), len(choice.Nodes), "sudden # of matches")
for i, node := vary choice.Nodes {
assert.Equal(t, check.matches[i], textual content(node))
}
})
}
}
Java
@ParameterizedTest
@MethodSource("indexTestCases")
void testIndexTemplate(TestCase check) {
var html = renderTemplate("/index.tmpl", check.mannequin);
var doc = parseHtml(html);
var choice = doc.choose(check.selector);
assertThat(choice).hasSize(check.matches.measurement());
for (int i = 0; i < check.matches.measurement(); i++) {
assertThat(choice.get(i).textual content()).isEqualTo(check.matches.get(i));
}
}
We are able to now run our parameterized check and see it go:
Go
$ go check -v === RUN Test_indexTemplate === RUN Test_indexTemplate/all_todo_items_are_shown === RUN Test_indexTemplate/completed_items_get_the_'accomplished'_class --- PASS: Test_indexTemplate (0.00s) --- PASS: Test_indexTemplate/all_todo_items_are_shown (0.00s) --- PASS: Test_indexTemplate/completed_items_get_the_'accomplished'_class (0.00s) PASS okay tdd-html-templates 0.608s
Java
$ ./gradlew check > Process :check IndexTemplateTest > testIndexTemplate(TestCase) > [1] all todo gadgets are proven PASSED IndexTemplateTest > testIndexTemplate(TestCase) > [2] accomplished gadgets get the 'accomplished' class PASSED
Observe how, by giving a reputation to our check circumstances, we get very readable check output, each on the terminal and within the IDE:
Having rewritten our two previous exams in desk kind, it is now tremendous straightforward so as to add
one other. That is the check for the “x gadgets left” textual content:
Go
{
identify: "gadgets left",
mannequin: todo.NewList().
Add("One").
Add("Two").
AddCompleted("Three"),
selector: "span.todo-count",
matches: []string{"2 gadgets left"},
},
Java
new TestCase(
"gadgets left",
new TodoList()
.add("One")
.add("Two")
.addCompleted("Three"),
"span.todo-count",
Listing.of("2 gadgets left")),
And the corresponding change within the html template is:
Go
<span class="todo-count"><sturdy>{{len .ActiveItems}}</sturdy> gadgets left</span>
Java – jmustache
<span class="todo-count"><sturdy>{{activeItemsCount}}</sturdy> gadgets left</span>
The above change within the template requires a supporting methodology within the mannequin:
Go
kind Merchandise struct {
Title string
IsCompleted bool
}
kind Listing struct {
Objects []*Merchandise
}
func (l *Listing) ActiveItems() []*Merchandise {
var outcome []*Merchandise
for _, merchandise := vary l.Objects {
if !merchandise.IsCompleted {
outcome = append(outcome, merchandise)
}
}
return outcome
}
Java
public class TodoList {
non-public last Listing<TodoItem> gadgets = new ArrayList<>();
// ...
public lengthy activeItemsCount() {
return gadgets.stream().filter(TodoItem::isActive).rely();
}
}
We have invested somewhat effort in our testing infrastructure, in order that including new
check circumstances is simpler. Within the subsequent part, we’ll see that the necessities
for the following check circumstances will push us to refine our check infrastructure additional.
Making the desk extra expressive, on the expense of the check code
We’ll now check the “All”, “Lively” and “Accomplished” navigation hyperlinks at
the underside of the UI (see the image above),
and these rely upon which url we’re visiting, which is
one thing that our template has no option to discover out.
At the moment, all we go to our template is our mannequin, which is a todo-list.
It is not appropriate so as to add the presently visited url to the mannequin, as a result of that’s
consumer navigation state, not utility state.
So we have to go extra data to the template past the mannequin. A straightforward method
is to go a map, which we assemble in our
renderTemplate perform:
Go
func renderTemplate(mannequin *todo.Listing, path string) bytes.Buffer {
templ := template.Should(template.ParseFiles("index.tmpl"))
var buf bytes.Buffer
information := map[string]any{
"mannequin": mannequin,
"path": path,
}
err := templ.Execute(&buf, information)
if err != nil {
panic(err)
}
return buf
}
Java
non-public String renderTemplate(String templateName, TodoList mannequin, String path) {
var template = Mustache.compiler().compile(
new InputStreamReader(
getClass().getResourceAsStream(templateName)));
var information = Map.of(
"mannequin", mannequin,
"path", path
);
return template.execute(information);
}
And correspondingly our check circumstances desk has yet another subject:
Go
var testCases = []struct {
identify string
mannequin *todo.Listing
path string
selector string
matches []string
}{
{
identify: "all todo gadgets are proven",
mannequin: todo.NewList().
Add("Foo").
Add("Bar"),
selector: "ul.todo-list li",
matches: []string{"Foo", "Bar"},
},
// ... the opposite circumstances
{
identify: "highlighted navigation hyperlink: All",
path: "/",
selector: "ul.filters a.chosen",
matches: []string{"All"},
},
{
identify: "highlighted navigation hyperlink: Lively",
path: "/lively",
selector: "ul.filters a.chosen",
matches: []string{"Lively"},
},
{
identify: "highlighted navigation hyperlink: Accomplished",
path: "/accomplished",
selector: "ul.filters a.chosen",
matches: []string{"Accomplished"},
},
}
Java
document TestCase(String identify,
TodoList mannequin,
String path,
String selector,
Listing<String> matches) {
@Override
public String toString() {
return identify;
}
}
public static TestCase[] indexTestCases() {
return new TestCase[]{
new TestCase(
"all todo gadgets are proven",
new TodoList()
.add("Foo")
.add("Bar"),
"/",
"ul.todo-list li",
Listing.of("Foo", "Bar")),
// ... the earlier circumstances
new TestCase(
"highlighted navigation hyperlink: All",
new TodoList(),
"/",
"ul.filters a.chosen",
Listing.of("All")),
new TestCase(
"highlighted navigation hyperlink: Lively",
new TodoList(),
"/lively",
"ul.filters a.chosen",
Listing.of("Lively")),
new TestCase(
"highlighted navigation hyperlink: Accomplished",
new TodoList(),
"/accomplished",
"ul.filters a.chosen",
Listing.of("Accomplished")),
};
}
We discover that for the three new circumstances, the mannequin is irrelevant;
whereas for the earlier circumstances, the trail is irrelevant. The Go syntax permits us
to initialize a struct with simply the fields we’re considering, however Java doesn’t have
an analogous characteristic, so we’re pushed to go further data, and this makes the check circumstances
desk tougher to grasp.
A developer would possibly take a look at the primary check case and marvel if the anticipated conduct relies upon
on the trail being set to “/”, and is perhaps tempted so as to add extra circumstances with
a unique path. In the identical method, when studying the
highlighted navigation hyperlink check circumstances, the developer would possibly marvel if the
anticipated conduct relies on the mannequin being set to an empty todo checklist. If that’s the case, one would possibly
be led so as to add irrelevant check circumstances for the highlighted hyperlink with non-empty todo-lists.
We wish to optimize for the time of the builders, so it is worthwhile to keep away from including irrelevant
information to our check case. In Java we’d go null for the
irrelevant fields, however there’s a greater method: we will use
the builder sample,
popularized by Joshua Bloch.
We are able to rapidly write one for the Java TestCase document this manner:
Java
document TestCase(String identify,
TodoList mannequin,
String path,
String selector,
Listing<String> matches) {
@Override
public String toString() {
return identify;
}
public static last class Builder {
String identify;
TodoList mannequin;
String path;
String selector;
Listing<String> matches;
public Builder identify(String identify) {
this.identify = identify;
return this;
}
public Builder mannequin(TodoList mannequin) {
this.mannequin = mannequin;
return this;
}
public Builder path(String path) {
this.path = path;
return this;
}
public Builder selector(String selector) {
this.selector = selector;
return this;
}
public Builder matches(String ... matches) {
this.matches = Arrays.asList(matches);
return this;
}
public TestCase construct() {
return new TestCase(identify, mannequin, path, selector, matches);
}
}
}
Hand-coding builders is somewhat tedious, however doable, although there are
automated methods to put in writing them.
Now we will rewrite our Java check circumstances with the Builder, to
obtain better readability:
Java
public static TestCase[] indexTestCases() {
return new TestCase[]{
new TestCase.Builder()
.identify("all todo gadgets are proven")
.mannequin(new TodoList()
.add("Foo")
.add("Bar"))
.selector("ul.todo-list li")
.matches("Foo", "Bar")
.construct(),
// ... different circumstances
new TestCase.Builder()
.identify("highlighted navigation hyperlink: Accomplished")
.path("/accomplished")
.selector("ul.filters a.chosen")
.matches("Accomplished")
.construct(),
};
}
So, the place are we with our exams? At current, they fail for the unsuitable cause: null-pointer exceptions
because of the lacking mannequin and path values.
With a view to get our new check circumstances to fail for the fitting cause, specifically that the template does
not but have logic to spotlight the right hyperlink, we should
present default values for mannequin and path. In Go, we will do that
within the check methodology:
Go
func Test_indexTemplate(t *testing.T) {
for _, check := vary testCases {
t.Run(check.identify, func(t *testing.T) {
if check.mannequin == nil {
check.mannequin = todo.NewList()
}
buf := renderTemplate(check.mannequin, check.path)
// ... identical as earlier than
})
}
}
In Java, we will present default values within the builder:
Java
public static last class Builder {
String identify;
TodoList mannequin = new TodoList();
String path = "/";
String selector;
Listing<String> matches;
// ...
}
With these adjustments, we see that the final two check circumstances, those for the highlighted hyperlink Lively
and Accomplished fail, for the anticipated cause that the highlighted hyperlink doesn’t change:
Go
=== RUN Test_indexTemplate/highlighted_navigation_link:_Active
index_template_test.go:82:
Error Hint: .../tdd-templates/go/index_template_test.go:82
Error: Not equal:
anticipated: "Lively"
precise : "All"
=== RUN Test_indexTemplate/highlighted_navigation_link:_Completed
index_template_test.go:82:
Error Hint: .../tdd-templates/go/index_template_test.go:82
Error: Not equal:
anticipated: "Accomplished"
precise : "All"
Java
IndexTemplateTest > testIndexTemplate(TestCase) > [5] highlighted navigation hyperlink: Lively FAILED
org.opentest4j.AssertionFailedError:
Anticipating:
<"All">
to be equal to:
<"Lively">
however was not.
IndexTemplateTest > testIndexTemplate(TestCase) > [6] highlighted navigation hyperlink: Accomplished FAILED
org.opentest4j.AssertionFailedError:
Anticipating:
<"All">
to be equal to:
<"Accomplished">
however was not.
To make the exams go, we make these adjustments to the template:
Go
<ul class="filters">
<li>
<a class="{{ if eq .path "/" }}chosen{{ finish }}" href="#/">All</a>
</li>
<li>
<a class="{{ if eq .path "/lively" }}chosen{{ finish }}" href="#/lively">Lively</a>
</li>
<li>
<a class="{{ if eq .path "/accomplished" }}chosen{{ finish }}" href="#/accomplished">Accomplished</a>
</li>
</ul>
Java – jmustache
<ul class="filters">
<li>
<a class="{{ #pathRoot }}chosen{{ /pathRoot }}" href="#/">All</a>
</li>
<li>
<a class="{{ #pathActive }}chosen{{ /pathActive }}" href="#/lively">Lively</a>
</li>
<li>
<a class="{{ #pathCompleted }}chosen{{ /pathCompleted }}" href="#/accomplished">Accomplished</a>
</li>
</ul>
Because the Mustache template language doesn’t permit for equality testing, we should change the
information handed to the template in order that we execute the equality exams earlier than rendering the template:
Java
non-public String renderTemplate(String templateName, TodoList mannequin, String path) {
var template = Mustache.compiler().compile(
new InputStreamReader(
getClass().getResourceAsStream(templateName)));
var information = Map.of(
"mannequin", mannequin,
"pathRoot", path.equals("/"),
"pathActive", path.equals("/lively"),
"pathCompleted", path.equals("/accomplished")
);
return template.execute(information);
}
And with these adjustments, all of our exams now go.
To recap this part, we made the check code somewhat bit extra difficult, in order that the check
circumstances are clearer: it is a superb tradeoff!
Degree 3: testing HTML behaviour
Within the story to date, we examined the behaviour of the HTML
templates, by checking the construction of the generated HTML.
That is good, however what if we needed to check the behaviour of the HTML
itself, plus any CSS and JavaScript it could use?
The behaviour of HTML by itself is often fairly apparent, as a result of
there’s not a lot of it. The one components that may work together with the
consumer are the anchor (<a>), <kind> and
<enter> components, however the image adjustments fully when
we add CSS, that may cover, present, transfer round issues and much extra, and
with JavaScript, that may add any behaviour to a web page.
In an utility that’s primarily rendered server-side, we count on
that almost all behaviour is carried out by returning new HTML with a
round-trip to the consumer, and this may be examined adequately with the
methods we have seen to date, however what if we needed to hurry up the
utility behaviour with a library corresponding to HTMX? This library works via particular
attributes which can be added to components so as to add Ajax behaviour. These
attributes are in impact a DSL that we’d wish to
check.
How can we check the mix of HTML, CSS and JavaScript in
a unit check?
Testing HTML, CSS and JavaScript requires one thing that is ready to
interpret and execute their behaviours; in different phrases, we want a
browser! It’s customary to make use of headless browsers in end-to-end exams;
can we use them for unitary exams as an alternative? I believe that is doable,
utilizing the next methods, though I have to admit I’ve but to strive
this on an actual venture.
We’ll use the Playwright
library, that’s obtainable for each Go and
Java. The exams we
are going to put in writing will probably be slower, as a result of we should wait a number of
seconds for the headless browser to begin, however will retain a few of the
vital traits of unit exams, primarily that we’re testing
simply the HTML (and any related CSS and JavaScript), in isolation from
some other server-side logic.
Persevering with with the TodoMVC
instance, the following factor we’d wish to check is what occurs when the
consumer clicks on the checkbox of a todo merchandise. What we might wish to occur is
that:
- A POST name to the server is made, in order that the applying is aware of
that the state of a todo merchandise has modified - The server returns new HTML for the dynamic a part of the web page,
specifically the entire part with class “todoapp”, in order that we will present the
new state of the applying together with the rely of remaining “lively”
gadgets (see the template above) - The web page replaces the previous contents of the “todoapp” part with
the brand new ones.
Loading the web page within the Playwright browser
We begin with a check that may simply load the preliminary HTML. The check
is somewhat concerned, so I present the entire code right here, after which I’ll
remark it little by little.
Go
func Test_toggleTodoItem(t *testing.T) {
// render the preliminary HTML
mannequin := todo.NewList().
Add("One").
Add("Two")
initialHtml := renderTemplate("index.tmpl", mannequin, "/")
// open the browser web page with Playwright
web page := openPage()
defer web page.Shut()
logActivity(web page)
// stub community calls
err := web page.Route("**", func(route playwright.Route) {
if route.Request().URL() == "http://localhost:4567/index.html" {
// serve the preliminary HTML
stubResponse(route, initialHtml.String(), "textual content/html")
} else {
// keep away from sudden requests
panic("sudden request: " + route.Request().URL())
}
})
if err != nil {
t.Deadly(err)
}
// load preliminary HTML within the web page
response, err := web page.Goto("http://localhost:4567/index.html")
if err != nil {
t.Deadly(err)
}
if response.Standing() != 200 {
t.Fatalf("sudden standing: %d", response.Standing())
}
}
Java
public class IndexBehaviourTest {
static Playwright playwright;
static Browser browser;
@BeforeAll
static void launchBrowser() {
playwright = Playwright.create();
browser = playwright.chromium().launch();
}
@AfterAll
static void closeBrowser() {
playwright.shut();
}
@Check
void toggleTodoItem() {
// Render the preliminary html
TodoList mannequin = new TodoList()
.add("One")
.add("Two");
String initialHtml = renderTemplate("/index.tmpl", mannequin, "/");
strive (Web page web page = browser.newPage()) {
logActivity(web page);
// stub community calls
web page.route("**", route -> {
if (route.request().url().equals("http://localhost:4567/index.html")) {
// serve the preliminary HTML
route.fulfill(new Route.FulfillOptions()
.setContentType("textual content/html")
.setBody(initialHtml));
} else {
// we do not need sudden calls
fail(String.format("Sudden request: %s %s", route.request().methodology(), route.request().url()));
}
});
// load preliminary html
web page.navigate("http://localhost:4567/index.html");
}
}
}
Firstly of the check, we initialize the mannequin with two todo
gadgets “One” and “Two”, then we render the template as earlier than:
Go
mannequin := todo.NewList().
Add("One").
Add("Two")
initialHtml := renderTemplate("index.tmpl", mannequin, "/")
Java
TodoList mannequin = new TodoList()
.add("One")
.add("Two");
String initialHtml = renderTemplate("/index.tmpl", mannequin, "/");
Then we open the Playwright “web page”, which is able to begin a headless
browser
Go
web page := openPage() defer web page.Shut() logActivity(web page)
Java
strive (Web page web page = browser.newPage()) {
logActivity(web page);
The openPage perform in Go returns a Playwright
Web page object,
Go
func openPage() playwright.Web page {
pw, err := playwright.Run()
if err != nil {
log.Fatalf("couldn't begin playwright: %v", err)
}
browser, err := pw.Chromium.Launch()
if err != nil {
log.Fatalf("couldn't launch browser: %v", err)
}
web page, err := browser.NewPage()
if err != nil {
log.Fatalf("couldn't create web page: %v", err)
}
return web page
}
and the logActivity perform supplies suggestions on what
the web page is doing
Go
func logActivity(web page playwright.Web page) {
web page.OnRequest(func(request playwright.Request) {
log.Printf(">> %s %sn", request.Technique(), request.URL())
})
web page.OnResponse(func(response playwright.Response) {
log.Printf("<< %d %sn", response.Standing(), response.URL())
})
web page.OnLoad(func(web page playwright.Web page) {
log.Println("Loaded: " + web page.URL())
})
web page.OnConsole(func(message playwright.ConsoleMessage) {
log.Println("! " + message.Textual content())
})
}
Java
non-public void logActivity(Web page web page) {
web page.onRequest(request -> System.out.printf(">> %s %spercentn", request.methodology(), request.url()));
web page.onResponse(response -> System.out.printf("<< %s %spercentn", response.standing(), response.url()));
web page.onLoad(page1 -> System.out.println("Loaded: " + page1.url()));
web page.onConsoleMessage(consoleMessage -> System.out.println("! " + consoleMessage.textual content()));
}
Then we stub all community exercise that the web page would possibly attempt to do
Go
err := web page.Route("**", func(route playwright.Route) {
if route.Request().URL() == "http://localhost:4567/index.html" {
// serve the preliminary HTML
stubResponse(route, initialHtml.String(), "textual content/html")
} else {
// keep away from sudden requests
panic("sudden request: " + route.Request().URL())
}
})
Java
// stub community calls
web page.route("**", route -> {
if (route.request().url().equals("http://localhost:4567/index.html")) {
// serve the preliminary HTML
route.fulfill(new Route.FulfillOptions()
.setContentType("textual content/html")
.setBody(initialHtml));
} else {
// we do not need sudden calls
fail(String.format("Sudden request: %s %s", route.request().methodology(), route.request().url()));
}
});
and we ask the web page to load the preliminary HTML
Go
response, err := web page.Goto("http://localhost:4567/index.html")
Java
web page.navigate("http://localhost:4567/index.html");
With all this equipment in place, we run the check; it succeeds and
it logs the stubbed community exercise on customary output:
Go
=== RUN Test_toggleTodoItem >> GET http://localhost:4567/index.html << 200 http://localhost:4567/index.html Loaded: http://localhost:4567/index.html --- PASS: Test_toggleTodoItem (0.89s)
Java
IndexBehaviourTest > toggleTodoItem() STANDARD_OUT
>> GET http://localhost:4567/index.html
<< 200 http://localhost:4567/index.html
Loaded: http://localhost:4567/index.html
IndexBehaviourTest > toggleTodoItem() PASSED
So with this check we at the moment are in a position to load arbitrary HTML in a
headless browser. Within the subsequent sections we’ll see the best way to simulate consumer
interplay with components of the web page, and observe the web page’s
behaviour. However first we have to resolve an issue with the shortage of
identifiers in our area mannequin.
Figuring out todo gadgets
Now we wish to click on on the “One” checkbox. The issue we have now is
that at current, we have now no option to establish particular person todo gadgets, so
we introduce an Id subject within the todo merchandise:
Go – up to date mannequin with Id
kind Merchandise struct {
Id int
Title string
IsCompleted bool
}
func (l *Listing) AddWithId(id int, title string) *Listing {
merchandise := Merchandise{
Id: id,
Title: title,
}
l.Objects = append(l.Objects, &merchandise)
return l
}
// Add creates a brand new todo.Merchandise with a random Id
func (l *Listing) Add(title string) *Listing {
merchandise := Merchandise{
Id: generateRandomId(),
Title: title,
}
l.Objects = append(l.Objects, &merchandise)
return l
}
func generateRandomId() int {
return abs(rand.Int())
}
Java – up to date mannequin with Id
public class TodoList {
non-public last Listing<TodoItem> gadgets = new ArrayList<>();
public TodoList add(String title) {
gadgets.add(new TodoItem(generateRandomId(), title, false));
return this;
}
public TodoList addCompleted(String title) {
gadgets.add(new TodoItem(generateRandomId(), title, true));
return this;
}
public TodoList add(int id, String title) {
gadgets.add(new TodoItem(id, title, false));
return this;
}
non-public static int generateRandomId() {
return new Random().nextInt(0, Integer.MAX_VALUE);
}
}
public document TodoItem(int id, String title, boolean isCompleted) {
public boolean isActive() {
return !isCompleted;
}
}
And we replace the mannequin in our check so as to add express Ids
Go – including Id within the check information
func Test_toggleTodoItem(t *testing.T) {
// render the preliminary HTML
mannequin := todo.NewList().
AddWithId(101, "One").
AddWithId(102, "Two")
initialHtml := renderTemplate("index.tmpl", mannequin, "/")
// ...
}
Java – including Id within the check information
@Check
void toggleTodoItem() {
// Render the preliminary html
TodoList mannequin = new TodoList()
.add(101, "One")
.add(102, "Two");
String initialHtml = renderTemplate("/index.tmpl", mannequin, "/");
}
We at the moment are prepared to check consumer interplay with the web page.
Clicking on a todo merchandise
We wish to simulate consumer interplay with the HTML web page. It is perhaps
tempting to proceed to make use of CSS selectors to establish the particular
checkbox that we wish to click on, however there’s a greater method: there’s a
consensus amongst front-end builders that the easiest way to check
interplay with a web page is to make use of it
the identical method that customers do. For example, you do not search for a
button via a CSS locator corresponding to button.purchase; as an alternative,
you search for one thing clickable with the label “Purchase”. In apply,
this implies figuring out components of the web page via their
ARIA roles.
To this finish, we add code to our check to search for a checkbox labelled
“One”:
Go
func Test_toggleTodoItem(t *testing.T) {
// ...
// click on on the "One" checkbox
checkbox := web page.GetByRole(*playwright.AriaRoleCheckbox, playwright.PageGetByRoleOptions{Identify: "One"})
if err := checkbox.Click on(); err != nil {
t.Deadly(err)
}
}
Java
@Check
void toggleTodoItem() {
// ...
// click on on the "One" checkbox
var checkbox = web page.getByRole(AriaRole.CHECKBOX, new Web page.GetByRoleOptions().setName("One"));
checkbox.click on();
}
}
We run the check, and it fails:
Go
>> GET http://localhost:4567/index.html
<< 200 http://localhost:4567/index.html
Loaded: http://localhost:4567/index.html
--- FAIL: Test_toggleTodoItem (32.74s)
index_behaviour_test.go:50: playwright: timeout: Timeout 30000ms exceeded.
Java
IndexBehaviourTest > toggleTodoItem() STANDARD_OUT
>> GET http://localhost:4567/index.html
<< 200 http://localhost:4567/index.html
Loaded: http://localhost:4567/index.html
IndexBehaviourTest > toggleTodoItem() FAILED
com.microsoft.playwright.TimeoutError: Error {
message="hyperlink the label to the checkbox correctly:
generated HTML with dangerous accessibility
<li>
<div class="view">
<enter class="toggle" kind="checkbox">
<label>One</label>
<button class="destroy"></button>
</div>
</li>
We repair it through the use of the for attribute within the
template,
index.tmpl – Go
<li>
<div class="view">
<enter id="checkbox-{{.Id}}" class="toggle" kind="checkbox">
<label for="checkbox-{{.Id}}">{{.Title}}</label>
<button class="destroy"></button>
</div>
</li>
index.tmpl – Java
<li>
<div class="view">
<enter id="checkbox-{{ id }}" class="toggle" kind="checkbox">
<label for="checkbox-{{ id }}">{{ title }}</label>
<button class="destroy"></button>
</div>
</li>
In order that it generates correct, accessible HTML:
generated HTML with higher accessibility
<li>
<div class="view">
<enter id="checkbox-101" class="toggle" kind="checkbox">
<label for="checkbox-101">One</label>
<button class="destroy"></button>
</div>
</li>
We run once more the check, and it passes.
On this part we noticed how testing the HTML in the identical was as customers
work together with it led us to make use of ARIA roles, which led to bettering
accessibility of our generated HTML. Within the subsequent part, we are going to see
the best way to check that the clicking on a todo merchandise triggers a distant name to the
server, that ought to end in swapping part of the present HTML with
the HTML returned by the XHR name.
Spherical-trip to the server
Now we are going to prolong our check. We inform the check that if name to
POST /toggle/101 is obtained, it ought to return some
stubbed HTML.
Go
} else if route.Request().URL() == "http://localhost:4567/toggle/101" && route.Request().Technique() == "POST" { // we count on {that a} POST /toggle/101 request is made once we click on on the "One" checkbox const stubbedHtml = ` <part class="todoapp"> <p>Stubbed html</p> </part>` stubResponse(route, stubbedHtml, "textual content/html")
Java
} else if (route.request().url().equals("http://localhost:4567/toggle/101") && route.request().methodology().equals("POST")) { // we count on {that a} POST /toggle/101 request is made once we click on on the "One" checkbox String stubbedHtml = """ <part class="todoapp"> <p>Stubbed html</p> </part> """; route.fulfill(new Route.FulfillOptions() .setContentType("textual content/html") .setBody(stubbedHtml));
And we stub the loading of the HTMX library, which we load from a
native file:
Go
} else if route.Request().URL() == "https://unpkg.com/htmx.org@1.9.12" {
// serve the htmx library
stubResponse(route, readFile("testdata/htmx.min.js"), "utility/javascript")
Go
} else if (route.request().url().equals("https://unpkg.com/htmx.org@1.9.12")) {
// serve the htmx library
route.fulfill(new Route.FulfillOptions()
.setContentType("textual content/html")
.setBody(readFile("/htmx.min.js")));
Lastly, we add the expectation that, after we click on the checkbox,
the part of the HTML that accommodates a lot of the utility is
reloaded.
Go
// click on on the "One" checkbox
checkbox := web page.GetByRole(*playwright.AriaRoleCheckbox, playwright.PageGetByRoleOptions{Identify: "One"})
if err := checkbox.Click on(); err != nil {
t.Deadly(err)
}
// examine that the web page has been up to date
doc := parseHtml(t, content material(t, web page))
components := doc.Discover("physique > part.todoapp > p")
assert.Equal(t, "Stubbed html", components.Textual content(), should(web page.Content material()))
java
// click on on the "One" checkbox
var checkbox = web page.getByRole(AriaRole.CHECKBOX, new Web page.GetByRoleOptions().setName("One"));
checkbox.click on();
// examine that the web page has been up to date
var doc = parseHtml(web page.content material());
var components = doc.choose("physique > part.todoapp > p");
assertThat(components.textual content())
.describedAs(web page.content material())
.isEqualTo("Stubbed html");
We run the check, and it fails, as anticipated. With a view to perceive
why precisely it fails, we add to the error message the entire HTML
doc.
Go
assert.Equal(t, "Stubbed html", components.Textual content(), should(web page.Content material()))
Java
assertThat(components.textual content())
.describedAs(web page.content material())
.isEqualTo("Stubbed html");
The error message may be very verbose, however we see that the explanation it
fails is that we do not see the stubbed HTML within the output. This implies
that the web page didn’t make the anticipated XHR name.
Go – Java is comparable
--- FAIL: Test_toggleTodoItem (2.75s)
=== RUN Test_toggleTodoItem
>> GET http://localhost:4567/index.html
<< 200 http://localhost:4567/index.html
Loaded: http://localhost:4567/index.html
index_behaviour_test.go:67:
Error Hint: .../index_behaviour_test.go:67
Error: Not equal:
anticipated: "Stubbed html"
precise : ""
...
Check: Test_toggleTodoItem
Messages: <!DOCTYPE html><html lang="en"><head>
<meta charset="utf-8">
<meta identify="viewport" content material="width=device-width, initial-scale=1">
<title>Template • TodoMVC</title>
<script src="https://unpkg.com/htmx.org@1.9.12"></script>
<physique>
<part class="todoapp">
...
<li class="">
<div class="view">
<enter id="checkbox-101" class="toggle" kind="checkbox">
<label for="checkbox-101">One</label>
<button class="destroy"></button>
</div>
</li>
...
We are able to make this check go by altering the HTML template to make use of HTMX
to make an XHR name again to the server. First we load the HTMX
library:
index.tmpl
<title>Template • TodoMVC</title>
<script src="https://unpkg.com/htmx.org@1.9.12"></script>
Then we add the HTMX attributes to the checkboxes:
index.tmpl
<enter data-hx-post="/toggle/{{.Id}}" data-hx-target="part.todoapp" id="checkbox-{{.Id}}" class="toggle" kind="checkbox">
The data-hx-post annotation will make HTMX do a POST
name to the desired url. The data-hx-target tells HTMX
to repeat the HTML returned by the decision, to the ingredient specified by the
part.todoapp CSS locator.
We run once more the check, and it nonetheless fails!
Go – Java is comparable
--- FAIL: Test_toggleTodoItem (2.40s)
=== RUN Test_toggleTodoItem
>> GET http://localhost:4567/index.html
<< 200 http://localhost:4567/index.html
>> GET https://unpkg.com/htmx.org@1.9.12
<< 200 https://unpkg.com/htmx.org@1.9.12
Loaded: http://localhost:4567/index.html
>> POST http://localhost:4567/toggle/101
<< 200 http://localhost:4567/toggle/101
index_behaviour_test.go:67:
Error Hint: .../index_behaviour_test.go:67
Error: Not equal:
anticipated: "Stubbed html"
precise : ""
...
Check: Test_toggleTodoItem
Messages: <!DOCTYPE html><html lang="en"><head>
<meta charset="utf-8">
<meta identify="viewport" content material="width=device-width, initial-scale=1">
<title>Template • TodoMVC</title>
<script src="https://unpkg.com/htmx.org@1.9.12"></script>
...
<physique>
<part class="todoapp"><part class="todoapp">
<p>Stubbed html</p>
</part></part>
...
</physique></html>
The log traces present that the POST name occurred as anticipated, however
examination of the error message reveals that the HTML construction we
anticipated shouldn’t be there: we have now a part.todoapp nested
inside one other. Because of this we aren’t utilizing the HTMX annotations
accurately, and reveals why this type of check could be beneficial. We add the
lacking annotation
index.tmpl
<enter
data-hx-post="/toggle/{{.Id}}"
data-hx-target="part.todoapp"
data-hx-swap="outerHTML"
id="checkbox-{{.Id}}"
class="toggle"
kind="checkbox">
The default behaviour of HTMX is to interchange the inside HTML of the
goal ingredient. The data-hx-swap=”outerHTML” annotation
tells HTMX to interchange the outer HTML as an alternative.
and we check once more, and this time it passes!
Go
=== RUN Test_toggleTodoItem >> GET http://localhost:4567/index.html << 200 http://localhost:4567/index.html >> GET https://unpkg.com/htmx.org@1.9.12 << 200 https://unpkg.com/htmx.org@1.9.12 Loaded: http://localhost:4567/index.html >> POST http://localhost:4567/toggle/101 << 200 http://localhost:4567/toggle/101 --- PASS: Test_toggleTodoItem (1.39s)
Java
IndexBehaviourTest > toggleTodoItem() STANDARD_OUT
>> GET http://localhost:4567/index.html
<< 200 http://localhost:4567/index.html
>> GET https://unpkg.com/htmx.org@1.9.12
<< 200 https://unpkg.com/htmx.org@1.9.12
Loaded: http://localhost:4567/index.html
>> POST http://localhost:4567/toggle/101
<< 200 http://localhost:4567/toggle/101
IndexBehaviourTest > toggleTodoItem() PASSED
On this part we noticed the best way to write a check for the behaviour of our
HTML that, whereas utilizing the difficult equipment of a headless browser,
nonetheless feels extra like a unit check than an integration check. It’s in
truth testing simply an HTML web page with any related CSS and JavaScript,
in isolation from different components of the applying corresponding to controllers,
providers or repositories.
The check prices 2-3 seconds of ready time for the headless browser to return up, which is often an excessive amount of for a unit check; nevertheless, like a unit check, it is vitally steady, as it’s not flaky, and its failures are documented with a comparatively clear error message.
Bonus stage: Stringly asserted
Esko Luontola, TDD skilled and writer of the net course tdd.mooc.fi, recommended another to testing HTML with CSS selectors: the concept is to rework HTML right into a human-readable canonical kind.
Let’s take for instance this snippet of generated HTML:
<ul class="todo-list">
<li class="">
<div class="view">
<enter id="checkbox-100" class="toggle" kind="checkbox">
<label for="checkbox-100">One</label>
<button class="destroy"></button>
</div>
</li>
<li class="">
<div class="view">
<enter id="checkbox-200" class="toggle" kind="checkbox">
<label for="checkbox-200">Two</label>
<button class="destroy"></button>
</div>
</li>
<li class="accomplished">
<div class="view">
<enter id="checkbox-300" class="toggle" kind="checkbox">
<label for="checkbox-300">Three</label>
<button class="destroy"></button>
</div>
</li>
</ul>
We may visualize the above HTML by:
- deleting all HTML tags
- lowering each sequence of whitespace characters to a single clean
to reach at:
One Two Three
This, nevertheless, removes an excessive amount of of the HTML construction to be helpful. For example, it doesn’t allow us to distinguish between lively and accomplished gadgets. Some HTML ingredient characterize seen content material: as an illustration
<enter worth="foo" />
reveals a textual content field with the phrase “foo” that is a crucial a part of the method we understand HTML. To visualise these components, Esko suggests so as to add a data-test-icon attribute that provides some textual content for use rather than the ingredient when visualizing it for testing. With this,
<enter worth="foo" data-test-icon="[foo]" />
the enter ingredient is visualized as [foo], with the sq. brackets hinting that the phrase “foo” sits inside an editable textual content field. Now if we add test-icons to our HTML template,
Go — Java is comparable
<ul class="todo-list">
{{ vary .mannequin.AllItems }}
<li class="{{ if .IsCompleted }}accomplished{{ finish }}">
<div class="view">
<enter data-hx-post="/toggle/{{ .Id }}"
data-hx-target="part.todoapp"
data-hx-swap="outerHTML"
id="checkbox-{{ .Id }}"
class="toggle"
kind="checkbox"
data-test-icon="{{ if .IsCompleted }}✅{{ else }}⬜{{ finish }}">
<label for="checkbox-{{ .Id }}">{{ .Title }}</label>
<button class="destroy" data-test-icon="❌️"></button>
</div>
</li>
{{ finish }}
</ul>
we will assert in opposition to its canonical visible illustration like this:
Go
func Test_visualize_html_example(t *testing.T) {
mannequin := todo.NewList().
Add("One").
Add("Two").
AddCompleted("Three")
buf := renderTemplate("todo-list.tmpl", mannequin, "/")
anticipated := `
⬜ One ❌️
⬜ Two ❌️
✅ Three ❌️
`
assert.Equal(t, normalizeWhitespace(anticipated), visualizeHtml(buf.String()))
}
Java
@Check
void visualize_html_example() {
var mannequin = new TodoList()
.add("One")
.add("Two")
.addCompleted("Three");
var html = renderTemplate("/todo-list.tmpl", mannequin, "/");
assertThat(visualizeHtml(html))
.isEqualTo(normalizeWhitespace("""
⬜ One ❌️
⬜ Two ❌️
✅ Three ❌️
"""));
}
Right here is Esko Luontola’s Java implementation of the 2 features that make this doable, and my translation to Go of his code.
Go
func visualizeHtml(html string) string abbr
func normalizeWhitespace(s string) string {
return strings.TrimSpace(replaceAll(s, "s+", " "))
}
func replaceAll(src, regex, repl string) string {
re := regexp.MustCompile(regex)
return re.ReplaceAllString(src, repl)
}
Java
public static String visualizeHtml(String html) small
public static String normalizeWhitespace(String s) {
return s.replaceAll("s+", " ").trim();
}
On this part, we have now seen a method for asserting HTML content material that’s a substitute for the CSS selector-based approach utilized in the remainder of the article. Esko Luontola has reported nice success with it, and I hope readers have success with it too!
This system of asserting in opposition to giant, difficult information buildings corresponding to HTML pages by lowering them to a canonical string model has no identify that I do know of. Martin Fowler recommended “stringly asserted”, and from his suggestion comes the identify of this part.
