add script to determine PR target branch in GitLab CI

.ci/integTestGen/Project.toml

@@ -4,6 +4,8 @@ authors = ["Simeon Ehrig <[email protected]>"]
 version = "0.1.0"
 
 [deps]
+HTTP = "cd3eb016-35fb-5094-929b-558a96fad6f3"
+JSON = "682c06a0-de6a-54ab-a142-c8b1cf79cde6"
 Pkg = "44cfe95a-1eb2-52ea-b672-e2afdf69b78f"
 PkgDependency = "9eb5382b-762c-48ca-8139-e736883fe800"
 YAML = "ddb6d928-2868-570f-bddf-ab3f9cf99eb6"

.ci/integTestGen/src/get_target_branch.jl

@@ -0,0 +1,71 @@
+module getTargetBranch
+
+using HTTP
+using JSON
+
+"""
+    get_target_branch()::AbstractString
+
+Returns the name of the target branch of the pull request. The function is required for our special
+setup where we mirror a PR from GitHub to GitLab CI. No merge request will be open on GitLab.
+Instead, a feature branch will be created and the commit will be pushed. As a result, we lose
+information about the original PR. So we need to use the GitHub Rest API to get the information
+depending on the repository name and PR number.
+"""
+function get_target_branch()::AbstractString
+    # GitLab CI provides the environemnt variable with the following pattern
+    # # pr-<PR number>/<repo owner of the source branch>/<project name>/<source branch name> 
+    # e.g. pr-41/SimeonEhrig/QED.jl/setDevDepDeps
+    if !haskey(ENV, "CI_COMMIT_REF_NAME")
+        error("Environment variable CI_COMMIT_REF_NAME is not set.")
+    end
+
+    splited_commit_ref_name = split(ENV["CI_COMMIT_REF_NAME"], "/")
+
+    if (!startswith(splited_commit_ref_name[1], "pr-"))
+        error("CI_COMMIT_REF_NAME does not start with pr-")
+    end
+
+    # parse to Int only to check if it is a number
+    pr_number = parse(Int, splited_commit_ref_name[1][(length("pr-") + 1):end])
+    if (pr_number <= 0)
+        error(
+            "a PR number always needs to be a positive integer number bigger than 0: $pr_number",
+        )
+    end
+
+    repository_name = splited_commit_ref_name[3]
+
+    try
+        headers = (
+            ("Accept", "application/vnd.github+json"),
+            ("X-GitHub-Api-Version", "2022-11-28"),
+        )
+        # in all cases, we assume that the PR targets the repositories in QEDjl-project
+        # there is no environment variable with the information, if the target repository is
+        # the upstream repository or a fork.
+        url = "https://api.github.com/repos/QEDjl-project/$repository_name/pulls/$pr_number"
+        response = HTTP.get(url, headers)
+        response_text = String(response.body)
+        repository_data = JSON.parse(response_text)
+        return repository_data["base"]["ref"]
+    catch e
+        # if for unknown reason, the PR does not exist, use fallback the dev branch
+        if isa(e, HTTP.Exceptions.StatusError) && e.status == 404
+            return "dev"
+        else
+            # Only the HTML code 404, page does not exist is handled. All other error will abort
+            # the script.  
+            throw(e)
+        end
+    end
+
+    return "dev"
+end
+
+if abspath(PROGRAM_FILE) == @__FILE__
+    target_branch = get_target_branch()
+    println(target_branch)
+end
+
+end

.ci/integTestGen/test/get_target_branch_data/pr_not_exist.json

@@ -0,0 +1,6 @@
+{
+    "message": "Not Found",
+    "documentation_url": "https://docs.github.com/rest/pulls/pulls#get-a-pull-request",
+    "status": "404"
+  }
+