add skip ci functionality (#28075)

Adds the possibility to skip workflow execution if the commit message
contains a string like [skip ci] or similar.

The default strings are the same as on GitHub, users can also set custom
ones in app.ini

Reference:
https://docs.github.com/en/actions/managing-workflow-runs/skipping-workflow-runs

Close #28020

tests/integration/actions_trigger_test.go

@@ -4,6 +4,7 @@
 package integration
 
 import (
+	"fmt"
 	"net/url"
 	"strings"
 	"testing"
@@ -18,6 +19,7 @@ import (
 	user_model "code.gitea.io/gitea/models/user"
 	actions_module "code.gitea.io/gitea/modules/actions"
 	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/setting"
 	pull_service "code.gitea.io/gitea/services/pull"
 	repo_service "code.gitea.io/gitea/services/repository"
 	files_service "code.gitea.io/gitea/services/repository/files"
@@ -194,3 +196,92 @@ func TestPullRequestTargetEvent(t *testing.T) {
 		assert.Equal(t, 1, unittest.GetCount(t, &actions_model.ActionRun{RepoID: baseRepo.ID}))
 	})
 }
+
+func TestSkipCI(t *testing.T) {
+	onGiteaRun(t, func(t *testing.T, u *url.URL) {
+		user2 := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 2})
+
+		// create the repo
+		repo, err := repo_service.CreateRepository(db.DefaultContext, user2, user2, repo_service.CreateRepoOptions{
+			Name:          "skip-ci",
+			Description:   "test skip ci functionality",
+			AutoInit:      true,
+			Gitignores:    "Go",
+			License:       "MIT",
+			Readme:        "Default",
+			DefaultBranch: "main",
+			IsPrivate:     false,
+		})
+		assert.NoError(t, err)
+		assert.NotEmpty(t, repo)
+
+		// enable actions
+		err = repo_model.UpdateRepositoryUnits(db.DefaultContext, repo, []repo_model.RepoUnit{{
+			RepoID: repo.ID,
+			Type:   unit_model.TypeActions,
+		}}, nil)
+		assert.NoError(t, err)
+
+		// add workflow file to the repo
+		addWorkflowToBaseResp, err := files_service.ChangeRepoFiles(git.DefaultContext, repo, user2, &files_service.ChangeRepoFilesOptions{
+			Files: []*files_service.ChangeRepoFile{
+				{
+					Operation:     "create",
+					TreePath:      ".gitea/workflows/pr.yml",
+					ContentReader: strings.NewReader("name: test\non:\n  push:\njobs:\n  test:\n    runs-on: ubuntu-latest\n    steps:\n      - run: echo helloworld\n"),
+				},
+			},
+			Message:   "add workflow",
+			OldBranch: "main",
+			NewBranch: "main",
+			Author: &files_service.IdentityOptions{
+				Name:  user2.Name,
+				Email: user2.Email,
+			},
+			Committer: &files_service.IdentityOptions{
+				Name:  user2.Name,
+				Email: user2.Email,
+			},
+			Dates: &files_service.CommitDateOptions{
+				Author:    time.Now(),
+				Committer: time.Now(),
+			},
+		})
+		assert.NoError(t, err)
+		assert.NotEmpty(t, addWorkflowToBaseResp)
+
+		// a run has been created
+		assert.Equal(t, 1, unittest.GetCount(t, &actions_model.ActionRun{RepoID: repo.ID}))
+
+		// add a file with a configured skip-ci string in commit message
+		addFileResp, err := files_service.ChangeRepoFiles(git.DefaultContext, repo, user2, &files_service.ChangeRepoFilesOptions{
+			Files: []*files_service.ChangeRepoFile{
+				{
+					Operation:     "create",
+					TreePath:      "bar.txt",
+					ContentReader: strings.NewReader("bar"),
+				},
+			},
+			Message:   fmt.Sprintf("%s add bar", setting.Actions.SkipWorkflowStrings[0]),
+			OldBranch: "main",
+			NewBranch: "main",
+			Author: &files_service.IdentityOptions{
+				Name:  user2.Name,
+				Email: user2.Email,
+			},
+			Committer: &files_service.IdentityOptions{
+				Name:  user2.Name,
+				Email: user2.Email,
+			},
+			Dates: &files_service.CommitDateOptions{
+				Author:    time.Now(),
+				Committer: time.Now(),
+			},
+		})
+		assert.NoError(t, err)
+		assert.NotEmpty(t, addFileResp)
+
+		// the commit message contains a configured skip-ci string, so there is still only 1 record
+		assert.Equal(t, 1, unittest.GetCount(t, &actions_model.ActionRun{RepoID: repo.ID}))
+	})
+}