Add new WebDriver methods, better arg merging and error logging (#414)

* Add ElementGetText and ElementSendKeys.

* Accommodate single-hyphen args, too.

args in moz:firefoxOptions use the "-" prefix, compared to args in
"goog:chromeOptions" using the "--" prefix.

* Detail error origin when launching a driver.

go/metadata/capabilities/capabilities.go

@@ -720,6 +720,9 @@ func mergeLists(m1, m2 []interface{}) []interface{} {
 	return nl
 }
 
+// The mergeArgs function merges m1 and m2. For same argument exists in m1 and m2 and has
+// prefix "--" or "-", the argument in m2 will override m1; If the same argument does not
+// have prefix "--" or "-", then both same arguments in m1 and m2 will remain.
 func mergeArgs(m1, m2 []interface{}) []interface{} {
 	m2Opts := map[string]bool{}
 
@@ -730,7 +733,7 @@ func mergeArgs(m1, m2 []interface{}) []interface{} {
 				m2Opts[arg[7:]] = true
 				continue // And leave arg out of m2Copy
 			}
-			if strings.HasPrefix(arg, "--") {
+			if strings.HasPrefix(arg, "-") {
 				tokens := strings.Split(arg, "=")
 				m2Opts[tokens[0]] = true
 			}
@@ -742,7 +745,7 @@ func mergeArgs(m1, m2 []interface{}) []interface{} {
 
 	for _, a := range m1 {
 		if arg, ok := a.(string); ok {
-			if strings.HasPrefix(arg, "--") {
+			if strings.HasPrefix(arg, "-") {
 				tokens := strings.Split(arg, "=")
 				// Skip options from m1 that are redefined in m2
 				if m2Opts[tokens[0]] {

go/metadata/capabilities/capabilities_test.go

@@ -435,7 +435,6 @@ func TestMerge(t *testing.T) {
 					"an option",
 					"--anOption",
 					"--anOption=true",
-					"-anotherOption",
 					map[string]interface{}{
 						"some": "map",
 					},
@@ -450,7 +449,7 @@ func TestMerge(t *testing.T) {
 			},
 		},
 		{
-			name: "args -- redefines",
+			name: "overrides '--' prefixed args",
 			input1: map[string]interface{}{
 				"args": []interface{}{
 					"an option",
@@ -531,6 +530,31 @@ func TestMerge(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "overrides '-' prefixed args",
+			input1: map[string]interface{}{
+				"args": []interface{}{
+					"option",
+					"--anOption",
+					"-width=1024",
+				},
+			},
+			input2: map[string]interface{}{
+				"args": []interface{}{
+					"option",
+					"--anOption",
+					"-width=2048",
+				},
+			},
+			result: map[string]interface{}{
+				"args": []interface{}{
+					"option",
+					"option",
+					"--anOption",
+					"-width=2048",
+				},
+			},
+		},
 		{
 			name: "chromeOptions to goog:chromeOptions",
 			input1: map[string]interface{}{
@@ -1600,3 +1624,4 @@ func TestMergeUnder(t *testing.T) {
 		})
 	}
 }
+

go/webdriver/webdriver.go

@@ -72,6 +72,10 @@ type WebDriver interface {
 	Screenshot(context.Context) (image.Image, error)
 	// ElementScreenshot takes a screenshot of the visible region encompassed by the bounding rectangle of element.
 	ElementScreenshot(ctx context.Context, el WebElement) (image.Image, error)
+	// ElementGetText gets the text of an element.
+	ElementGetText(ctx context.Context, el WebElement) (string, error)
+	// ElementSendKeys sends keys to the element.
+	ElementSendKeys(ctx context.Context, el WebElement, keys string) error
 	// WindowHandles returns a slice of the current window handles.
 	WindowHandles(context.Context) ([]string, error)
 	// CurrentWindowHandle returns the handle of the active window.
@@ -393,6 +397,23 @@ func (d *webDriver) ElementScreenshot(ctx context.Context, el WebElement) (image
 	return png.Decode(base64.NewDecoder(base64.StdEncoding, strings.NewReader(value)))
 }
 
+// ElementGetText gets the text of an element.
+func (d *webDriver) ElementGetText(ctx context.Context, el WebElement) (string, error) {
+	var value string
+	if err := d.get(ctx, fmt.Sprintf("element/%s/text", el.ID()), &value); err != nil {
+		return "", err
+	}
+	return value, nil
+}
+
+// ElementSendKeys sends keys to an element.
+func (d *webDriver) ElementSendKeys(ctx context.Context, el WebElement, keys string) error {
+	if err := d.post(ctx, fmt.Sprintf("element/%s/value", el.ID()), map[string]string{"text": keys}, nil); err != nil {
+		return err
+	}
+	return nil
+}
+
 // WindowHandles returns a slice of the current window handles.
 func (d *webDriver) WindowHandles(ctx context.Context) ([]string, error) {
 	var value []string

go/wsl/hub/hub.go

@@ -155,7 +155,7 @@ func (h *Hub) newSessionFromCaps(ctx context.Context, caps *capabilities.Capabil
 		if err := resolver.RecyclePorts(); err != nil {
 			log.Printf("Error recycling ports: %v", err)
 		}
-		return "", nil, err
+		return "", nil, fmt.Errorf("Error launching driver binary: %w", err)
 	}
 
 	s, err := d.NewSession(ctx, caps, w)
@@ -165,7 +165,7 @@ func (h *Hub) newSessionFromCaps(ctx context.Context, caps *capabilities.Capabil
 		if err := d.Shutdown(ctx); err != nil {
 			log.Printf("Error shutting down driver: %v", err)
 		}
-		return "", nil, err
+		return "", nil, fmt.Errorf("Error requesting new session: %w", err)
 	}
 
 	return s, d, nil