Handle git exceptions in wiki create and update services

In this commit, we wrap git operations when creating and updating
wiki pages, in order to avoid throwing git errors when operations
fails.

Changelog: fixed

app/models/wiki.rb

@@ -278,6 +278,19 @@ class Wiki
     @repository = nil
   end
 
+  def capture_git_error(action, &block)
+    yield block
+  rescue Gitlab::Git::Index::IndexError,
+         Gitlab::Git::CommitError,
+         Gitlab::Git::PreReceiveError,
+         Gitlab::Git::CommandError,
+         ArgumentError => error
+
+    Gitlab::ErrorTracking.log_exception(error, action: action, wiki_id: id)
+
+    false
+  end
+
   private
 
   def multi_commit_options(action, message = nil, title = nil)
@@ -311,19 +324,6 @@ class Wiki
     "#{user.username} #{action} page: #{title}"
   end
 
-  def capture_git_error(action, &block)
-    yield block
-  rescue Gitlab::Git::Index::IndexError,
-         Gitlab::Git::CommitError,
-         Gitlab::Git::PreReceiveError,
-         Gitlab::Git::CommandError,
-         ArgumentError => error
-
-    Gitlab::ErrorTracking.log_exception(error, action: action, wiki_id: id)
-
-    false
-  end
-
   def change_head_to_default_branch
     repository.raw_repository.write_ref('HEAD', "refs/heads/#{default_branch}")
   end

app/services/wiki_pages/create_service.rb

@@ -6,11 +6,12 @@ module WikiPages
       wiki = Wiki.for_container(container, current_user)
       page = WikiPage.new(wiki)
 
-      if page.create(@params)
-        execute_hooks(page)
+      wiki.capture_git_error(event_action) do
+        page.create(@params)
       end
 
       if page.persisted?
+        execute_hooks(page)
         ServiceResponse.success(payload: { page: page })
       else
         ServiceResponse.error(message: _('Could not create wiki page'), payload: { page: page })

app/services/wiki_pages/update_service.rb

@@ -8,7 +8,7 @@ module WikiPages
       # this class is not thread safe!
       @old_slug = page.slug
 
-      if page.update(@params)
+      if page.wiki.capture_git_error(event_action) { page.update(@params) }
         execute_hooks(page)
         ServiceResponse.success(payload: { page: page })
       else

spec/services/wiki_pages/create_service_spec.rb

@@ -4,4 +4,24 @@ require 'spec_helper'
 
 RSpec.describe WikiPages::CreateService do
   it_behaves_like 'WikiPages::CreateService#execute', :project
+
+  describe '#execute' do
+    let_it_be(:project) { create(:project) }
+
+    subject(:service) { described_class.new(container: project) }
+
+    context 'when wiki create fails due to git error' do
+      let(:wiki_git_error) { 'Could not create wiki page' }
+
+      it 'catches the thrown error and returns a ServiceResponse error' do
+        allow_next_instance_of(WikiPage) do |instance|
+          allow(instance).to receive(:create).and_raise(Gitlab::Git::CommandError.new(wiki_git_error))
+        end
+
+        result = service.execute
+        expect(result).to be_error
+        expect(result.message).to eq(wiki_git_error)
+      end
+    end
+  end
 end

spec/services/wiki_pages/update_service_spec.rb

@@ -4,4 +4,26 @@ require 'spec_helper'
 
 RSpec.describe WikiPages::UpdateService do
   it_behaves_like 'WikiPages::UpdateService#execute', :project
+
+  describe '#execute' do
+    let_it_be(:project) { create(:project) }
+
+    let(:page) { create(:wiki_page, project: project) }
+
+    subject(:service) { described_class.new(container: project) }
+
+    context 'when wiki create fails due to git error' do
+      let(:wiki_git_error) { 'Could not update wiki page' }
+
+      it 'catches the thrown error and returns a ServiceResponse error' do
+        allow_next_instance_of(WikiPage) do |instance|
+          allow(instance).to receive(:update).and_raise(Gitlab::Git::CommandError.new(wiki_git_error))
+        end
+
+        result = service.execute(page)
+        expect(result).to be_error
+        expect(result.message).to eq(wiki_git_error)
+      end
+    end
+  end
 end