feat(cel): enable string and list extension functions in CEL expressions

pkg/cel/cel.go

@@ -9,6 +9,7 @@ import (
 	"github.com/google/cel-go/common/decls"
 	"github.com/google/cel-go/common/types"
 	"github.com/google/cel-go/common/types/ref"
+	"github.com/google/cel-go/ext"
 )
 
 func evaluate(expr string, env *cel.Env, data map[string]any) (ref.Val, error) {
@@ -90,7 +91,10 @@ func Value(query string, body any, headers, pacParams map[string]string, changed
 			decls.NewVariable("pull_request_labels", types.StringType),
 			decls.NewVariable("pull_request_number", types.StringType),
 			decls.NewVariable("git_auth_secret", types.StringType),
-		))
+		),
+		ext.Strings(),
+		ext.Lists(),
+	)
 	val, err := evaluate(query, celDec, map[string]any{
 		"body":    jsonMap,
 		"pac":     pacParams,

pkg/templates/templating_test.go

@@ -175,6 +175,53 @@ func TestReplacePlaceHoldersVariables(t *testing.T) {
 				"hello": "world",
 			},
 		},
+		{
+			name:     "Test CEL with string join",
+			template: `all files: {{ files.all.join(", ") }}`,
+			expected: `all files: file1.txt, file2.txt, file3.txt`,
+			dicto: map[string]string{
+				"revision": "main",
+			},
+			changedFiles: map[string]any{
+				"all": []string{"file1.txt", "file2.txt", "file3.txt"},
+			},
+			headers: http.Header{
+				"Test": []string{"value"},
+			},
+			rawEvent: map[string]any{
+				"hello": "world",
+			},
+		},
+		{
+			name:     "Test CEL with string replace",
+			template: `{{ cel: trigger_comment.replace("bad", "good") }}`,
+			expected: `a good comment!`,
+			dicto: map[string]string{
+				"trigger_comment": "a bad comment!",
+			},
+			changedFiles: map[string]any{},
+			headers: http.Header{
+				"Test": []string{"value"},
+			},
+			rawEvent: map[string]any{
+				"hello": "world",
+			},
+		},
+		{
+			name:     "Test CEL with string substring",
+			template: `{{ cel: "HELLOWORLD".substring(0, 5) }}`,
+			expected: `HELLO`,
+			dicto: map[string]string{
+				"trigger_comment": "a bad comment!",
+			},
+			changedFiles: map[string]any{},
+			headers: http.Header{
+				"Test": []string{"value"},
+			},
+			rawEvent: map[string]any{
+				"hello": "world",
+			},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {

test/github_pullrequest_test.go

@@ -765,6 +765,34 @@ func TestGithubGHEPullRequestCelPrefix(t *testing.T) {
 	assert.NilError(t, err)
 }
 
+func TestGithubGHEPullRequestCELJoin(t *testing.T) {
+	ctx := context.Background()
+	g := &tgithub.PRTest{
+		Label:     "Github CEL String Join",
+		YamlFiles: []string{"testdata/pipelinerun-cel-string-join.yaml"},
+		GHE:       true,
+	}
+	g.RunPullRequest(ctx, t)
+	defer g.TearDown(ctx, t)
+
+	prs, err := g.Cnx.Clients.Tekton.TektonV1().PipelineRuns(g.TargetNamespace).List(ctx, metav1.ListOptions{})
+	assert.NilError(t, err)
+	assert.Assert(t, len(prs.Items) >= 1, "Expected at least one PipelineRun")
+
+	err = twait.RegexpMatchingInPodLog(
+		ctx,
+		g.Cnx,
+		g.TargetNamespace,
+		fmt.Sprintf("tekton.dev/pipelineRun=%s,tekton.dev/pipelineTask=cel-string-join-test", prs.Items[0].Name),
+		"step-test-cel-string-join-values",
+		*regexp.MustCompile(".*tekton/pipelinerun-cel-string-join.yaml"),
+		"",
+		2,
+		nil,
+	)
+	assert.NilError(t, err)
+}
+
 // Local Variables:
 // compile-command: "go test -tags=e2e -v -info TestGithubPullRequest$ ."
 // End:

test/testdata/pipelinerun-cel-string-join.yaml

@@ -0,0 +1,20 @@
+---
+apiVersion: tekton.dev/v1beta1
+kind: PipelineRun
+metadata:
+  name: "\\ .PipelineName //"
+  annotations:
+    pipelinesascode.tekton.dev/target-namespace: "\\ .TargetNamespace //"
+    pipelinesascode.tekton.dev/on-cel-expression: |
+      target_branch == "\\ .TargetBranch //" && event == "\\ .TargetEvent //"
+spec:
+  pipelineSpec:
+    tasks:
+      - name: cel-string-join-test
+        taskSpec:
+          steps:
+            - name: test-cel-string-join-values
+              image: registry.access.redhat.com/ubi10/ubi-micro
+              script: |
+                echo "{{ cel: files.all.join(", ") }}"
+                exit 0