Add project level git depth setting

Introduce default_git_depth in project's CI/CD settings and set it to
50. Use it if there is no GIT_DEPTH variable specified. Apply this
default only to newly created projects and keep it nil for old ones
in order to not break pipelines that rely on non-shallow clones.

default_git_depth can be updated from CI/CD Settings in the UI, must be
either nil or integer between 0 and 1000 (incl).

Inherit default_git_depth from the origin project when forking projects.

MR pipelines are run on a MR ref (refs/merge-requests/:iid/merge) and it
contains unique commit (i.e. merge commit) which doesn't exist in the
other branch/tags refs. We need to add it cause otherwise it may break
pipelines for old projects that have already enabled Pipelines for merge
results and have git depth 0.

Document new default_git_depth project CI/CD setting

1 files changed, 32 insertions, 22 deletions

diff --git a/spec/presenters/ci/build_runner_presenter_spec.rb b/spec/presenters/ci/build_runner_presenter_spec.rb
index 3430111ca9e..9ed8e3a4e0a 100644
--- a/spec/presenters/ci/build_runner_presenter_spec.rb
+++ b/spec/presenters/ci/build_runner_presenter_spec.rb
@@ -119,23 +119,23 @@ describe Ci::BuildRunnerPresenter do
   end
 
   describe '#git_depth' do
-    subject { presenter.git_depth }
-
     let(:build) { create(:ci_build) }
 
-    it 'returns the correct git depth' do
-      is_expected.to eq(0)
-    end
+    subject(:git_depth) { presenter.git_depth }
 
     context 'when GIT_DEPTH variable is specified' do
       before do
         create(:ci_pipeline_variable, key: 'GIT_DEPTH', value: 1, pipeline: build.pipeline)
       end
 
-      it 'returns the correct git depth' do
-        is_expected.to eq(1)
+      it 'returns its value' do
+        expect(git_depth).to eq(1)
       end
     end
+
+    it 'defaults to git depth setting for the project' do
+      expect(git_depth).to eq(build.project.default_git_depth)
+    end
   end
 
   describe '#refspecs' do
@@ -144,24 +144,24 @@ describe Ci::BuildRunnerPresenter do
     let(:build) { create(:ci_build) }
 
     it 'returns the correct refspecs' do
-      is_expected.to contain_exactly('+refs/tags/*:refs/tags/*',
-                                     '+refs/heads/*:refs/remotes/origin/*')
+      is_expected.to contain_exactly("+refs/heads/#{build.ref}:refs/remotes/origin/#{build.ref}")
     end
 
-    context 'when GIT_DEPTH variable is specified' do
-      before do
-        create(:ci_pipeline_variable, key: 'GIT_DEPTH', value: 1, pipeline: build.pipeline)
-      end
+    context 'when ref is tag' do
+      let(:build) { create(:ci_build, :tag) }
 
       it 'returns the correct refspecs' do
-        is_expected.to contain_exactly("+refs/heads/#{build.ref}:refs/remotes/origin/#{build.ref}")
+        is_expected.to contain_exactly("+refs/tags/#{build.ref}:refs/tags/#{build.ref}")
       end
 
-      context 'when ref is tag' do
-        let(:build) { create(:ci_build, :tag) }
+      context 'when GIT_DEPTH is zero' do
+        before do
+          create(:ci_pipeline_variable, key: 'GIT_DEPTH', value: 0, pipeline: build.pipeline)
+        end
 
         it 'returns the correct refspecs' do
-          is_expected.to contain_exactly("+refs/tags/#{build.ref}:refs/tags/#{build.ref}")
+          is_expected.to contain_exactly('+refs/tags/*:refs/tags/*',
+                                         '+refs/heads/*:refs/remotes/origin/*')
         end
       end
     end
@@ -173,17 +173,27 @@ describe Ci::BuildRunnerPresenter do
 
       it 'returns the correct refspecs' do
         is_expected
-          .to contain_exactly('+refs/heads/*:refs/remotes/origin/*',
-                              '+refs/tags/*:refs/tags/*',
-                              '+refs/merge-requests/1/head:refs/merge-requests/1/head')
+          .to contain_exactly('+refs/merge-requests/1/head:refs/merge-requests/1/head')
+      end
+
+      context 'when GIT_DEPTH is zero' do
+        before do
+          create(:ci_pipeline_variable, key: 'GIT_DEPTH', value: 0, pipeline: build.pipeline)
+        end
+
+        it 'returns the correct refspecs' do
+          is_expected
+            .to contain_exactly('+refs/merge-requests/1/head:refs/merge-requests/1/head',
+                                '+refs/heads/*:refs/remotes/origin/*',
+                                '+refs/tags/*:refs/tags/*')
+        end
       end
 
       context 'when pipeline is legacy detached merge request pipeline' do
         let(:merge_request) { create(:merge_request, :with_legacy_detached_merge_request_pipeline) }
 
         it 'returns the correct refspecs' do
-          is_expected.to contain_exactly('+refs/tags/*:refs/tags/*',
-                                         '+refs/heads/*:refs/remotes/origin/*')
+          is_expected.to contain_exactly("+refs/heads/#{build.ref}:refs/remotes/origin/#{build.ref}")
         end
       end
     end