Select button element by descendant image alt text

As with links, button elements may consistent entirely of an image. In
such cases, one may identify the button using the value of the
descendant image's alt attribute (as a screen reader would).

History.md

@@ -1,3 +1,8 @@
+#Edge
+
+### Changed
+* Select `<button>` elements with descendant images with `alt` attributes matching the locator [Ian Lesperance]
+
 #Version 2.9.2
 Release date: 2016-09-29
 

lib/capybara/selector.rb

@@ -157,7 +157,7 @@ end
 #
 #  Find buttons ( input [of type submit, reset, image, button] or button elements )
 #
-# @locator Matches the id, value, or title attributes, string content of a button, or the alt attribute of an image type button
+# @locator Matches the id, value, or title attributes, string content of a button, or the alt attribute of an image type button or of a descendant image of a button
 #
 # @filter [String] :id  Matches the id attribute
 # @filter [String] :title Matches the title attribute
@@ -177,7 +177,7 @@ Capybara.add_selector(:button) do
 
       input_btn_xpath = input_btn_xpath[locator_matches]
 
-      btn_xpath = btn_xpath[locator_matches | XPath.string.n.is(locator)]
+      btn_xpath = btn_xpath[locator_matches | XPath.string.n.is(locator) | XPath.descendant(:img)[XPath.attr(:alt).is(locator)]]
 
       alt_matches = XPath.attr(:alt).is(locator)
       alt_matches |= XPath.attr(:'aria-label').is(locator) if Capybara.enable_aria_label

lib/capybara/spec/session/click_button_spec.rb

@@ -338,6 +338,19 @@ Capybara::SpecHelper.spec '#click_button' do
       expect(extract_results(@session)['first_name']).to eq('John')
     end
   end
+
+  context "with descendant image alt given on a button defined by <button> tag" do
+    it "should submit the associated form" do
+      @session.click_button('A horse eating hay')
+      expect(extract_results(@session)['first_name']).to eq('John')
+    end
+
+    it "should work with partial matches" do
+      @session.click_button('se eating h')
+      expect(extract_results(@session)['first_name']).to eq('John')
+    end
+  end
+
   context "with a locator that doesn't exist" do
     it "should raise an error" do
       msg = "Unable to find button \"does not exist\""

lib/capybara/spec/views/form.erb

@@ -351,6 +351,7 @@ New line after and before textarea tag
     <button type="submit" id="click_me_123" title="Click Title button" value="click_me">Click me!</button>
     <button type="submit" name="form[no_value]">No Value!</button>
     <button id="no_type">No Type!</button>
+    <button><img alt="A horse eating hay"/></button>
     <input type="button" disabled="disabled" value="Disabled button"/>
   </p>