Playwright testing for commit diffs

includes:

- easier repo declaration for playwright tests by @Gusted
- full backend build for pushing Git repos by @Gusted
- playwright testing (which fails with the current diff algorithm, but
  passes with the new)
- disable eslint rule for conditional expect, because it defeats the
  purpose (working around it would result in much more complex test code
  in our cases)

tests/e2e/declare_repos_test.go

@@ -0,0 +1,83 @@
+// Copyright 2024 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package e2e
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+
+	unit_model "code.gitea.io/gitea/models/unit"
+	"code.gitea.io/gitea/models/unittest"
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/git"
+	files_service "code.gitea.io/gitea/services/repository/files"
+	"code.gitea.io/gitea/tests"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+type FileChanges [][]string
+
+// put your Git repo declarations in here
+// feel free to amend the helper function below or use the raw variant directly
+func DeclareGitRepos(t *testing.T) func() {
+	var cleanupFunctions []func()
+	cleanupFunctions = append(cleanupFunctions, newRepo(t, 2, "diff-test", FileChanges{
+		{"testfile", "hello", "hallo", "hola", "native", "ubuntu-latest", "- runs-on: ubuntu-latest", "- runs-on: debian-latest"},
+	}))
+
+	return func() {
+		for _, cleanup := range cleanupFunctions {
+			cleanup()
+		}
+	}
+}
+
+func newRepo(t *testing.T, userID int64, repoName string, fileChanges FileChanges) func() {
+	user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: userID})
+	somerepo, _, cleanupFunc := tests.CreateDeclarativeRepo(t, user, repoName,
+		[]unit_model.Type{unit_model.TypeCode, unit_model.TypeIssues}, nil,
+		nil,
+	)
+
+	for _, file := range fileChanges {
+		changeLen := len(file)
+		for i := 1; i < changeLen; i++ {
+			operation := "create"
+			if i != 1 {
+				operation = "update"
+			}
+			resp, err := files_service.ChangeRepoFiles(git.DefaultContext, somerepo, user, &files_service.ChangeRepoFilesOptions{
+				Files: []*files_service.ChangeRepoFile{{
+					Operation:     operation,
+					TreePath:      file[0],
+					ContentReader: strings.NewReader(file[i]),
+				}},
+				Message:   fmt.Sprintf("Patch: %s-%s", file[0], strconv.Itoa(i)),
+				OldBranch: "main",
+				NewBranch: "main",
+				Author: &files_service.IdentityOptions{
+					Name:  user.Name,
+					Email: user.Email,
+				},
+				Committer: &files_service.IdentityOptions{
+					Name:  user.Name,
+					Email: user.Email,
+				},
+				Dates: &files_service.CommitDateOptions{
+					Author:    time.Now(),
+					Committer: time.Now(),
+				},
+			})
+			require.NoError(t, err)
+			assert.NotEmpty(t, resp)
+		}
+	}
+
+	return cleanupFunc
+}