Add API for explicitly waiting for a condition to become true (#91)

Without this change, test developers are required to roll their own loops to poll when a condition becomes true. This API addition provides some syntactic sugar to cut down on boilerplate.
tebeka · Aug 21, 2017 · 988bde7 · 988bde7
1 parent 4adf11e
commit 988bde7
Show file tree

Hide file tree

Showing 4 changed files with 103 additions and 0 deletions.
diff --git a/.gitignore b/.gitignore
@@ -6,3 +6,5 @@ selenium-server-standalone-*.jar
 chromedriver*
 vendor/*
 !vendor/*.go
+coverage.txt
+coverage.out
diff --git a/remote.go b/remote.go
@@ -1124,6 +1124,45 @@ func (wd *remoteWD) Screenshot() ([]byte, error) {
 	return ioutil.ReadAll(decoder)
 }
 
+// Condition is an alias for a type that is passed as an argument
+// for selenium.Wait(cond Condition) (error) function.
+type Condition func(wd WebDriver) (bool, error)
+
+const (
+	// Default polling interval for selenium.Wait function.
+	DefaultWaitInterval = 100 * time.Millisecond
+
+	// Default timeout for selenium.Wait function.
+	DefaultWaitTimeout = 60 * time.Second
+)
+
+func (wd *remoteWD) WaitWithTimeoutAndInterval(condition Condition, timeout, interval time.Duration) error {
+	startTime := time.Now()
+
+	for {
+		done, err := condition(wd)
+		if err != nil {
+			return err
+		}
+		if done {
+			return nil
+		}
+
+		if elapsed := time.Since(startTime); elapsed > timeout {
+			return fmt.Errorf("timeout after %v", elapsed)
+		}
+		time.Sleep(interval)
+	}
+}
+
+func (wd *remoteWD) WaitWithTimeout(condition Condition, timeout time.Duration) error {
+	return wd.WaitWithTimeoutAndInterval(condition, timeout, DefaultWaitInterval)
+}
+
+func (wd *remoteWD) Wait(condition Condition) error {
+	return wd.WaitWithTimeoutAndInterval(condition, DefaultWaitTimeout, DefaultWaitInterval)
+}
+
 func (wd *remoteWD) Log(typ log.Type) ([]log.Message, error) {
 	url := wd.requestURL("/session/%s/log", wd.id)
 	params := map[string]log.Type{

diff --git a/remote_test.go b/remote_test.go
@@ -494,6 +494,7 @@ func runTests(t *testing.T, c config) {
 	t.Run("CSSProperty", runTest(testCSSProperty, c))
 	t.Run("Proxy", runTest(testProxy, c))
 	t.Run("SwitchFrame", runTest(testSwitchFrame, c))
+	t.Run("Wait", runTest(testWait, c))
 	t.Run("ActiveElement", runTest(testActiveElement, c))
 }
 
@@ -1633,6 +1634,42 @@ func testSwitchFrame(t *testing.T, c config) {
 	}
 }
 
+func testWait(t *testing.T, c config) {
+	const newTitle = "Title changed."
+	titleChangeCondition := func(wd WebDriver) (bool, error) {
+		title, err := wd.Title()
+		if err != nil {
+			return false, err
+		}
+
+		return title == newTitle, nil
+	}
+
+	wd := newRemote(t, c)
+	defer quitRemote(t, wd)
+
+	titleURL := serverURL + "/title"
+
+	if err := wd.Get(titleURL); err != nil {
+		t.Fatalf("wd.Get(%q) returned error: %v", titleURL, err)
+	}
+
+	// Testing when the title should change.
+	if err := wd.Wait(titleChangeCondition); err != nil {
+		t.Fatalf("wd.Wait(titleChangeCondition) returned error: %v", err)
+	}
+
+	// Reloading the page.
+	if err := wd.Get(titleURL); err != nil {
+		t.Fatalf("wd.Get(%q) returned error: %v", titleURL, err)
+	}
+
+	// Testing when the Wait() should error the timeout..
+	if err := wd.WaitWithTimeout(titleChangeCondition, 500*time.Millisecond); err == nil {
+		t.Fatalf("wd.Wait(titleChangeCondition) should returned error, but it didn't.")
+	}
+}
+
 var homePage = `
 <html>
 <head>
@@ -1708,6 +1745,21 @@ var framePage = `
 </html>
 `
 
+var titleChangePage = `
+<html>
+<head>
+	<title>Go Selenium Test Suite - Title Change Page</title>
+</head>
+<body>
+	This page will change a title after 1 second.
+
+	<script>
+		setTimeout(function() { document.title = 'Title changed.' }, 1000);
+	</script>
+</body>
+</html>
+`
+
 func handler(w http.ResponseWriter, r *http.Request) {
 	path := r.URL.Path
 	page, ok := map[string]string{
@@ -1716,6 +1768,7 @@ func handler(w http.ResponseWriter, r *http.Request) {
 		"/search": searchPage,
 		"/log":    logPage,
 		"/frame":  framePage,
+		"/title":  titleChangePage,
 	}[path]
 	if !ok {
 		http.NotFound(w, r)

diff --git a/selenium.go b/selenium.go
@@ -358,6 +358,15 @@ type WebDriver interface {
 	// ExecuteScriptAsyncRaw asynchronously executes a script but does not
 	// perform JSON decoding.
 	ExecuteScriptAsyncRaw(script string, args []interface{}) ([]byte, error)
+
+	// WaitWithTimeoutAndInterval waits for the condition to evaluate to true.
+	WaitWithTimeoutAndInterval(condition Condition, timeout, interval time.Duration) error
+
+	// WaitWithTimeout works like WaitWithTimeoutAndInterval, but with default polling interval.
+	WaitWithTimeout(condition Condition, timeout time.Duration) error
+
+	//Wait works like WaitWithTimeoutAndInterval, but using the default timeout and polling interval.
+	Wait(condition Condition) error
 }
 
 // WebElement defines method supported by web elements.