feat: support evaluation of concurrency clauses in runner (#827)

Pre-req for support `concurrency` clauses for Gitea Actions, later added to Gitea in PR: https://github.com/go-gitea/gitea/pull/32751. Unit tests added in this PR relative to upstream.

Squashes PRs https://gitea.com/gitea/act/pulls/124 & https://gitea.com/gitea/act/pulls/139, as noted in https://code.forgejo.org/forgejo/runner/issues/678

Reviewed-on: https://gitea.com/gitea/act/pulls/124
Reviewed-by: Lunny Xiao <lunny@noreply.gitea.com>
Co-authored-by: Zettat123 <zettat123@gmail.com>
Co-committed-by: Zettat123 <zettat123@gmail.com>
Reviewed-on: https://gitea.com/gitea/act/pulls/139
Reviewed-by: Zettat123 <zettat123@noreply.gitea.com>
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: ChristopherHX <christopher.homberger@web.de>
Co-committed-by: ChristopherHX <christopher.homberger@web.de>

<!--start release-notes-assistant-->
<!--URL:https://code.forgejo.org/forgejo/runner-->
- features
  - [PR](https://code.forgejo.org/forgejo/runner/pulls/827): <!--number 827 --><!--line 0 --><!--description ZmVhdDogc3VwcG9ydCBldmFsdWF0aW9uIG9mIGNvbmN1cnJlbmN5IGNsYXVzZXMgaW4gcnVubmVy-->feat: support evaluation of concurrency clauses in runner<!--description-->
<!--end release-notes-assistant-->

Reviewed-on: https://code.forgejo.org/forgejo/runner/pulls/827
Reviewed-by: earl-warren <earl-warren@noreply.code.forgejo.org>
Co-authored-by: Mathieu Fenniak <mathieu@fenniak.net>
Co-committed-by: Mathieu Fenniak <mathieu@fenniak.net>

act/model/workflow.go

@@ -25,7 +25,8 @@ type Workflow struct {
 	Jobs     map[string]*Job   `yaml:"jobs"`
 	Defaults Defaults          `yaml:"defaults"`
 
-	RawNotifications yaml.Node `yaml:"enable-email-notifications"`
+	RawNotifications yaml.Node       `yaml:"enable-email-notifications"`
+	RawConcurrency   *RawConcurrency `yaml:"concurrency"` // For Gitea
 }
 
 // On events for the workflow
@@ -806,3 +807,28 @@ func (w *Workflow) Notifications() (bool, error) {
 		return false, fmt.Errorf("enable-email-notifications: unknown type: %v", w.RawNotifications.Kind)
 	}
 }
+
+// For Gitea
+// RawConcurrency represents a workflow concurrency or a job concurrency with uninterpolated options
+type RawConcurrency struct {
+	Group            string `yaml:"group,omitempty"`
+	CancelInProgress string `yaml:"cancel-in-progress,omitempty"`
+	RawExpression    string `yaml:"-,omitempty"`
+}
+
+type objectConcurrency RawConcurrency
+
+func (r *RawConcurrency) UnmarshalYAML(n *yaml.Node) error {
+	if err := n.Decode(&r.RawExpression); err == nil {
+		return nil
+	}
+	return n.Decode((*objectConcurrency)(r))
+}
+
+func (r *RawConcurrency) MarshalYAML() (interface{}, error) {
+	if r.RawExpression != "" {
+		return r.RawExpression, nil
+	}
+
+	return (*objectConcurrency)(r), nil
+}

act/model/workflow_test.go

@@ -702,3 +702,48 @@ func TestStepUsesHash(t *testing.T) {
 		})
 	}
 }
+
+func TestReadWorkflow_Concurrency(t *testing.T) {
+	for _, testCase := range []struct {
+		expected *RawConcurrency
+		err      string
+		snippet  string
+	}{
+		{
+			expected: nil,
+			snippet:  "# nothing",
+		},
+		{
+			expected: &RawConcurrency{Group: "${{ github.workflow }}-${{ github.ref }}", CancelInProgress: ""},
+			snippet:  "concurrency: { group: \"${{ github.workflow }}-${{ github.ref }}\" }",
+		},
+		{
+			expected: &RawConcurrency{Group: "example-group", CancelInProgress: "true"},
+			snippet:  "concurrency: { group: example-group, cancel-in-progress: true }",
+		},
+	} {
+		t.Run(testCase.snippet, func(t *testing.T) {
+			yaml := fmt.Sprintf(`
+name: name-455
+on: push
+%s
+jobs:
+  valid-JOB-Name-455:
+    runs-on: docker
+    steps:
+      - run: echo hi
+`, testCase.snippet)
+
+			workflow, err := ReadWorkflow(strings.NewReader(yaml), true)
+			if testCase.err != "" {
+				assert.ErrorContains(t, err, testCase.err)
+			} else {
+				assert.NoError(t, err, "read workflow should succeed")
+
+				concurrency := workflow.RawConcurrency
+				// assert.NoError(t, err)
+				assert.Equal(t, testCase.expected, concurrency)
+			}
+		})
+	}
+}