Merge branch 'case-insensitive-ci-skip' into 'master'

Allow "ci skip" to be in any case

## What does this MR do?

This MR makes the check for the [ci skip] tag in a commit message case insensitive and adds support for [skip ci].

## Are there points in the code the reviewer needs to double check?

No.

## Why was this MR needed?

I couldn't understand why some of my commits were being built, even though they contained "[CI Skip]".

## What are the relevant issue numbers?
N/A
## Screenshots (if relevant)
N/A
## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4785

4 files changed, 51 insertions, 4 deletions

diff --git a/CHANGELOG b/CHANGELOG
index 4a8188ea060..7453630488b 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -11,6 +11,7 @@ v 8.10.0 (unreleased)
   - Fix changing issue state columns in milestone view
   - Fix user creation with stronger minimum password requirements !4054 (nathan-pmt)
   - Add API endpoint for a group issues !4520 (mahcsig)
+  - Allow [ci skip] to be in any case and allow [skip ci]. !4785 (simon_w)
 
 v 8.9.1
   - Refactor labels documentation. !3347
diff --git a/app/models/ci/pipeline.rb b/app/models/ci/pipeline.rb
index 0c9a5e42eec..10324bf2257 100644
--- a/app/models/ci/pipeline.rb
+++ b/app/models/ci/pipeline.rb
@@ -163,7 +163,7 @@ module Ci
     end
 
     def skip_ci?
-      git_commit_message =~ /(\[ci skip\])/ if git_commit_message
+      git_commit_message =~ /\[(ci skip|skip ci)\]/i if git_commit_message
     end
 
     def environments
diff --git a/doc/ci/yaml/README.md b/doc/ci/yaml/README.md
index 1892acda29b..d2d1b04f893 100644
--- a/doc/ci/yaml/README.md
+++ b/doc/ci/yaml/README.md
@@ -1034,8 +1034,8 @@ You can find the link under `/ci/lint` of your gitlab instance.
 
 ## Skipping builds
 
-If your commit message contains `[ci skip]`, the commit will be created but the
-builds will be skipped.
+If your commit message contains `[ci skip]` or `[skip ci]`, using any
+capitalization, the commit will be created but the builds will be skipped.
 
 ## Examples
 
diff --git a/spec/services/create_commit_builds_service_spec.rb b/spec/services/create_commit_builds_service_spec.rb
index deab242f45a..309213bd44c 100644
--- a/spec/services/create_commit_builds_service_spec.rb
+++ b/spec/services/create_commit_builds_service_spec.rb
@@ -83,6 +83,9 @@ describe CreateCommitBuildsService, services: true do
 
     context 'when commit contains a [ci skip] directive' do
       let(:message) { "some message[ci skip]" }
+      let(:messageFlip) { "some message[skip ci]" }
+      let(:capMessage) { "some message[CI SKIP]" }
+      let(:capMessageFlip) { "some message[SKIP CI]" }
 
       before do
         allow_any_instance_of(Ci::Pipeline).to receive(:git_commit_message) { message }
@@ -96,12 +99,55 @@ describe CreateCommitBuildsService, services: true do
                                    after: '31das312',
                                    commits: commits
                                   )
+
+        expect(pipeline).to be_persisted
+        expect(pipeline.builds.any?).to be false
+        expect(pipeline.status).to eq("skipped")
+      end
+
+      it "skips builds creation if there is [skip ci] tag in commit message" do
+        commits = [{ message: messageFlip }]
+        pipeline = service.execute(project, user,
+                                   ref: 'refs/tags/0_1',
+                                   before: '00000000',
+                                   after: '31das312',
+                                   commits: commits
+                                  )
+
+        expect(pipeline).to be_persisted
+        expect(pipeline.builds.any?).to be false
+        expect(pipeline.status).to eq("skipped")
+      end
+
+      it "skips builds creation if there is [CI SKIP] tag in commit message" do
+        commits = [{ message: capMessage }]
+        pipeline = service.execute(project, user,
+                                   ref: 'refs/tags/0_1',
+                                   before: '00000000',
+                                   after: '31das312',
+                                   commits: commits
+                                  )
+
+        expect(pipeline).to be_persisted
+        expect(pipeline.builds.any?).to be false
+        expect(pipeline.status).to eq("skipped")
+      end
+
+      it "skips builds creation if there is [SKIP CI] tag in commit message" do
+        commits = [{ message: capMessageFlip }]
+        pipeline = service.execute(project, user,
+                                   ref: 'refs/tags/0_1',
+                                   before: '00000000',
+                                   after: '31das312',
+                                   commits: commits
+                                  )
+
         expect(pipeline).to be_persisted
         expect(pipeline.builds.any?).to be false
         expect(pipeline.status).to eq("skipped")
       end
 
-      it "does not skips builds creation if there is no [ci skip] tag in commit message" do
+      it "does not skips builds creation if there is no [ci skip] or [skip ci] tag in commit message" do
         allow_any_instance_of(Ci::Pipeline).to receive(:git_commit_message) { "some message" }
 
         commits = [{ message: "some message" }]