Add API Endpoint for Branch Creation (#11607)

* [FEATURE] [API] Add Endpoint for Branch Creation

Issue: https://github.com/go-gitea/gitea/issues/11376

This commit introduces an API endpoint for branch creation.

The added route is POST /repos/{owner}/{repo}/branches.
A JSON with the name of the new branch and the name of the old branch is
required as parameters.

Signed-off-by: Terence Le Huu Phuong <terence@qwasar.io>

* Put all the logic into CreateBranch and removed CreateRepoBranch

* - Added the error ErrBranchDoesNotExist in error.go
- Made the CreateNewBranch function return an errBranchDoesNotExist error
when the OldBranch does not exist
- Made the CreateBranch API function checks that the repository is not
empty and that branch exists.

* - Added a resetFixtures helper function in integration_test.go to
fine-tune test env resetting
- Added api test for CreateBranch
- Used resetFixture instead of the more general prepareTestEnv in the
repo_branch_test CreateBranch tests

* Moved the resetFixtures call inside the loop for APICreateBranch function

* Put the prepareTestEnv back in repo_branch_test

* fix import order/sort api branch test

Co-authored-by: zeripath <art27@cantab.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/modules/repository/branch.go b/modules/repository/branch.go
index 418ba25c89..94be6f0f5a 100644
--- a/modules/repository/branch.go
+++ b/modules/repository/branch.go
@@ -71,7 +71,9 @@ func CreateNewBranch(doer *models.User, repo *models.Repository, oldBranchName,
 	}
 
 	if !git.IsBranchExist(repo.RepoPath(), oldBranchName) {
-		return fmt.Errorf("OldBranch: %s does not exist. Cannot create new branch from this", oldBranchName)
+		return models.ErrBranchDoesNotExist{
+			BranchName: oldBranchName,
+		}
 	}
 
 	basePath, err := models.CreateTemporaryPath("branch-maker")