Fix signature badge popover not showing on Firefox

Use anchor element instead of button to allow better cross-browser
support. This issue was observed in Firefox and Safari but not Chrome.

app/views/projects/commit/_signature_badge.html.haml

@@ -30,5 +30,5 @@
 
     = link_to(_('Learn more about signing commits'), help_page_path('user/project/repository/gpg_signed_commits/index.md'), class: 'gpg-popover-help-link')
 
-%button{ tabindex: 0, class: css_classes, data: { toggle: 'popover', html: 'true', placement: 'top', title: title, content: content } }
+%a{ role: 'button', tabindex: 0, class: css_classes, data: { toggle: 'popover', html: 'true', placement: 'top', title: title, content: content } }
   = label

changelogs/unreleased/fix-signature-badge-popover.yml

+---
+title: Fix signature badge popover on Firefox
+merge_request: 24756
+author:
+type: fixed

spec/features/signed_commits_spec.rb

@@ -15,8 +15,7 @@ describe 'GPG signed commits' do
 
     visit project_commit_path(project, ref)
 
-    expect(page).to have_button 'Unverified'
-    expect(page).not_to have_button 'Verified'
+    expect(page).to have_selector('.gpg-status-box', text: 'Unverified')
 
     # user changes their email which makes the gpg key verified
     perform_enqueued_jobs do
@@ -26,8 +25,7 @@ describe 'GPG signed commits' do
 
     visit project_commit_path(project, ref)
 
-    expect(page).not_to have_button 'Unverified'
-    expect(page).to have_button 'Verified'
+    expect(page).to have_selector('.gpg-status-box', text: 'Verified')
   end
 
   it 'changes from unverified to verified when the user adds the missing gpg key', :sidekiq_might_not_need_inline do
@@ -36,8 +34,7 @@ describe 'GPG signed commits' do
 
     visit project_commit_path(project, ref)
 
-    expect(page).to have_button 'Unverified'
-    expect(page).not_to have_button 'Verified'
+    expect(page).to have_selector('.gpg-status-box', text: 'Unverified')
 
     # user adds the gpg key which makes the signature valid
     perform_enqueued_jobs do
@@ -46,8 +43,7 @@ describe 'GPG signed commits' do
 
     visit project_commit_path(project, ref)
 
-    expect(page).not_to have_button 'Unverified'
-    expect(page).to have_button 'Verified'
+    expect(page).to have_selector('.gpg-status-box', text: 'Verified')
   end
 
   context 'shows popover badges', :js do
@@ -77,7 +73,7 @@ describe 'GPG signed commits' do
     it 'unverified signature' do
       visit project_commit_path(project, GpgHelpers::SIGNED_COMMIT_SHA)
 
-      click_on 'Unverified'
+      page.find('.gpg-status-box', text: 'Unverified').click
 
       within '.popover' do
         expect(page).to have_content 'This commit was signed with an unverified signature.'
@@ -90,7 +86,7 @@ describe 'GPG signed commits' do
 
       visit project_commit_path(project, GpgHelpers::DIFFERING_EMAIL_SHA)
 
-      click_on 'Unverified'
+      page.find('.gpg-status-box', text: 'Unverified').click
 
       within '.popover' do
         expect(page).to have_content 'This commit was signed with a verified signature, but the committer email is not verified to belong to the same user.'
@@ -105,7 +101,7 @@ describe 'GPG signed commits' do
 
       visit project_commit_path(project, GpgHelpers::SIGNED_COMMIT_SHA)
 
-      click_on 'Unverified'
+      page.find('.gpg-status-box', text: 'Unverified').click
 
       within '.popover' do
         expect(page).to have_content "This commit was signed with a different user's verified signature."
@@ -120,7 +116,7 @@ describe 'GPG signed commits' do
 
       visit project_commit_path(project, GpgHelpers::SIGNED_AND_AUTHORED_SHA)
 
-      click_on 'Verified'
+      page.find('.gpg-status-box', text: 'Verified').click
 
       within '.popover' do
         expect(page).to have_content 'This commit was signed with a verified signature and the committer email is verified to belong to the same user.'
@@ -136,13 +132,13 @@ describe 'GPG signed commits' do
       visit project_commit_path(project, GpgHelpers::SIGNED_AND_AUTHORED_SHA)
 
       # wait for the signature to get generated
-      expect(page).to have_button 'Verified'
+      expect(page).to have_selector('.gpg-status-box', text: 'Verified')
 
       user_1.destroy!
 
       refresh
 
-      click_on 'Verified'
+      page.find('.gpg-status-box', text: 'Verified').click
 
       within '.popover' do
         expect(page).to have_content 'This commit was signed with a verified signature and the committer email is verified to belong to the same user.'
@@ -160,9 +156,9 @@ describe 'GPG signed commits' do
       end
 
       it 'displays commit signature' do
-        expect(page).to have_button 'Unverified'
+        expect(page).to have_selector('.gpg-status-box', text: 'Unverified')
 
-        click_on 'Unverified'
+        page.find('.gpg-status-box', text: 'Unverified').click
 
         within '.popover' do
           expect(page).to have_content 'This commit was signed with an unverified signature'