feat: support workflow outputs on expanded reusable workflows (#10578)

Follow-up to #10525; adds support for `on.workflow_call.outputs` to expanded reusable workflows (when no `runs-on` is specified on a job that `uses: ...` another workflow).  When all the inner jobs of a workflow call complete, `on.workflow_call.outputs` is evaluated and the related outputs are stored on the outer job's `ActionTask`.

## Checklist

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### Tests

- I added test coverage for Go changes...
  - [x] in their respective `*_test.go` for unit tests.
  - [ ] in the `tests/integration` directory if it involves interactions with a live Forgejo server.
- I added test coverage for JavaScript changes...
  - [ ] in `web_src/js/*.test.js` if it can be unit tested.
  - [ ] in `tests/e2e/*.test.e2e.js` if it requires interactions with a live Forgejo server (see also the [developer guide for JavaScript testing](https://codeberg.org/forgejo/forgejo/src/branch/forgejo/tests/e2e/README.md#end-to-end-tests)).
- **end-to-end testing**: https://code.forgejo.org/forgejo/end-to-end/pulls/1322

### Documentation

- [x] I created a pull request [to the documentation](https://codeberg.org/forgejo/docs) to explain to Forgejo users how to use this change.
    - https://codeberg.org/forgejo/docs/pulls/1661
- [ ] I did not document these changes and I do not expect someone else to do it.

### Release notes

- [ ] I do not want this change to show in the release notes.
- [x] I want the title to show in the release notes with a link to this pull request.
- [ ] I want the content of the `release-notes/<pull request number>.md` to be be used for the release notes instead of the title.

<!--start release-notes-assistant-->

## Release notes
<!--URL:https://codeberg.org/forgejo/forgejo-->
- Features
  - [PR](https://codeberg.org/forgejo/forgejo/pulls/10578): <!--number 10578 --><!--line 0 --><!--description c3VwcG9ydCB3b3JrZmxvdyBvdXRwdXRzIG9uIGV4cGFuZGVkIHJldXNhYmxlIHdvcmtmbG93cw==-->support workflow outputs on expanded reusable workflows<!--description-->
<!--end release-notes-assistant-->

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/10578
Reviewed-by: Andreas Ahlenstorf <aahlenst@noreply.codeberg.org>
Co-authored-by: Mathieu Fenniak <mathieu@fenniak.net>
Co-committed-by: Mathieu Fenniak <mathieu@fenniak.net>

models/actions/run_job.go

@@ -234,7 +234,9 @@ func AggregateJobStatus(jobs []*ActionRunJob) Status {
 	}
 }
 
-func (job *ActionRunJob) decodeWorkflowPayload() (*jobparser.SingleWorkflow, error) {
+// Retrieves the parsed workflow for this specific job.  This field is often accessed multiple times in succession, so
+// the parsed content is cached in-memory on the `ActionRunJob` instance.
+func (job *ActionRunJob) DecodeWorkflowPayload() (*jobparser.SingleWorkflow, error) {
 	if job.workflowPayloadDecoded != nil {
 		return job.workflowPayloadDecoded, nil
 	}
@@ -259,7 +261,7 @@ func (job *ActionRunJob) ClearCachedWorkflowPayload() {
 // then regenerated and deleted.  If it is incomplete, and if the information is available, the specific job and/or
 // output that causes it to be incomplete will be returned as well.
 func (job *ActionRunJob) IsIncompleteMatrix() (bool, *jobparser.IncompleteNeeds, error) {
-	jobWorkflow, err := job.decodeWorkflowPayload()
+	jobWorkflow, err := job.DecodeWorkflowPayload()
 	if err != nil {
 		return false, nil, fmt.Errorf("failure decoding workflow payload: %w", err)
 	}
@@ -269,7 +271,7 @@ func (job *ActionRunJob) IsIncompleteMatrix() (bool, *jobparser.IncompleteNeeds,
 // Checks whether the target job has a `runs-on` field with an expression that requires an input from another job.  The
 // job will be blocked until the other job is complete, and then regenerated and deleted.
 func (job *ActionRunJob) IsIncompleteRunsOn() (bool, *jobparser.IncompleteNeeds, *jobparser.IncompleteMatrix, error) {
-	jobWorkflow, err := job.decodeWorkflowPayload()
+	jobWorkflow, err := job.DecodeWorkflowPayload()
 	if err != nil {
 		return false, nil, nil, fmt.Errorf("failure decoding workflow payload: %w", err)
 	}
@@ -279,7 +281,7 @@ func (job *ActionRunJob) IsIncompleteRunsOn() (bool, *jobparser.IncompleteNeeds,
 // Check whether this job is a caller of a reusable workflow -- in other words, the real work done in this job is in
 // spawned child jobs, not this job.
 func (job *ActionRunJob) IsWorkflowCallOuterJob() (bool, error) {
-	jobWorkflow, err := job.decodeWorkflowPayload()
+	jobWorkflow, err := job.DecodeWorkflowPayload()
 	if err != nil {
 		return false, fmt.Errorf("failure decoding workflow payload: %w", err)
 	}

services/actions/Test_tryHandleWorkflowCallOuterJob/action_task_output.yml

@@ -0,0 +1,6 @@
+# Case w/ action_run_job.id = 601
+-
+  id: 100
+  task_id: 100
+  output_key: my_output
+  output_value: 'abcdefghijklmnopqrstuvwxyz'

services/actions/Test_tryHandleWorkflowCallOuterJob/action_variable.yml

@@ -0,0 +1,22 @@
+# Case w/ action_run_job.id = 601
+-
+  id: 1001
+  name: REPO_VAR
+  owner_id: 0
+  repo_id: 63
+  data: "this is a repo variable"
+  created_unix: 1737000000
+-
+  id: 1002
+  name: ORG_VAR
+  owner_id: 2
+  repo_id: 0
+  data: "this is an org variable"
+  created_unix: 1737000000
+-
+  id: 1003
+  name: GLOBAL_VAR
+  owner_id: 0
+  repo_id: 0
+  data: "this is a global variable"
+  created_unix: 1737000000

services/actions/job_emitter.go

@@ -391,8 +391,49 @@ func tryHandleWorkflowCallOuterJob(ctx context.Context, job *actions_model.Actio
 		return nil, nil
 	}
 
-	// Insert a placeholder task; this will be used in the future to store computed outputs
-	actionTask, err := actions_model.CreatePlaceholderTask(ctx, job, map[string]string{})
+	// Gather all the data that is needed to perform an expression evaluation of the job's outputs:
+	singleWorkflow, err := job.DecodeWorkflowPayload()
+	if err != nil {
+		return nil, fmt.Errorf("failure to decode workflow payload: %w", err)
+	}
+	err = job.LoadRun(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failure to load job's run: %w", err)
+	}
+	err = job.Run.LoadRepo(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failure to load run's repo: %w", err)
+	}
+	githubContext := generateGiteaContextForRun(job.Run)
+	taskNeeds, err := FindTaskNeeds(ctx, job)
+	if err != nil {
+		return nil, fmt.Errorf("failure to 'needs' for job: %w", err)
+	}
+	needs := make([]string, 0, len(taskNeeds))
+	jobResults := make(map[string]string, len(taskNeeds))
+	jobOutputs := make(map[string]map[string]string, len(taskNeeds))
+	for jobID, n := range taskNeeds {
+		needs = append(needs, jobID)
+		jobResults[jobID] = n.Result.String()
+		jobOutputs[jobID] = n.Outputs
+	}
+	vars, err := actions_model.GetVariablesOfRun(ctx, job.Run)
+	if err != nil {
+		return nil, fmt.Errorf("failure to 'var' for run: %w", err)
+	}
+
+	// With all the required contexts, we can calculate the outputs.
+	outputs := jobparser.EvaluateWorkflowCallOutputs(
+		singleWorkflow,
+		githubContext,
+		vars,
+		needs,
+		jobResults,
+		jobOutputs,
+	)
+
+	// Insert a placeholder task with all the computed outputs
+	actionTask, err := actions_model.CreatePlaceholderTask(ctx, job, outputs)
 	if err != nil {
 		return nil, fmt.Errorf("failure to insert placeholder task: %w", err)
 	}

services/actions/job_emitter_test.go

@@ -440,7 +440,15 @@ func Test_tryHandleWorkflowCallOuterJob(t *testing.T) {
 			name:         "outputs for every context",
 			runJobID:     601,
 			updateFields: []string{"task_id"},
-			outputs:      map[string]string{},
+			outputs: map[string]string{
+				"from_inner_job":        "abcdefghijklmnopqrstuvwxyz",
+				"from_inner_job_result": "success",
+				"from_forgejo_ctx":      "refs/heads/main",
+				"from_input_ctx":        "hello, world!",
+				"from_vars_repo":        "this is a repo variable",
+				"from_vars_org":         "this is an org variable",
+				"from_vars_global":      "this is a global variable",
+			},
 		},
 	}
 	for _, tt := range tests {