Add runs-on label completions for mapping syntax (#273)

Provides runner label completions (ubuntu-latest, macos-latest, etc.)
when using the runs-on mapping syntax with the labels property:

  jobs:
    build:
      runs-on:
        labels: |

  jobs:
    build:
      runs-on:
        labels:
          - |

Previously, completions only worked for the simple runs-on syntax:

  jobs:
    build:
      runs-on: |

The fix registers the same value provider for both 'runs-on' and
'runs-on-labels' definition keys in the schema.

languageservice/src/complete.test.ts

@@ -825,4 +825,51 @@ jobs:
       expect(textEdit.newText).toEqual("runs-on:\n  - ");
     });
   });
+
+  describe("runs-on mapping syntax", () => {
+    it("provides label completions for labels as scalar", async () => {
+      const input = `on: push
+jobs:
+  build:
+    runs-on:
+      labels: |`;
+      const result = await complete(...getPositionFromCursor(input));
+
+      // Should show runner labels
+      expect(result.some(x => x.label === "ubuntu-latest")).toBe(true);
+      expect(result.some(x => x.label === "macos-latest")).toBe(true);
+      expect(result.some(x => x.label === "self-hosted")).toBe(true);
+    });
+
+    it("provides label completions for labels as sequence item", async () => {
+      const input = `on: push
+jobs:
+  build:
+    runs-on:
+      labels:
+        - |`;
+      const result = await complete(...getPositionFromCursor(input));
+
+      // Should show runner labels
+      expect(result.some(x => x.label === "ubuntu-latest")).toBe(true);
+      expect(result.some(x => x.label === "macos-latest")).toBe(true);
+      expect(result.some(x => x.label === "self-hosted")).toBe(true);
+    });
+
+    it("excludes already used labels in sequence", async () => {
+      const input = `on: push
+jobs:
+  build:
+    runs-on:
+      labels:
+        - ubuntu-latest
+        - |`;
+      const result = await complete(...getPositionFromCursor(input));
+
+      // Should NOT show ubuntu-latest since it's already in the list
+      expect(result.some(x => x.label === "ubuntu-latest")).toBe(false);
+      // But should show other labels
+      expect(result.some(x => x.label === "macos-latest")).toBe(true);
+    });
+  });
 });

languageservice/src/value-providers/default.ts

@@ -19,6 +19,11 @@ export const DEFAULT_RUNNER_LABELS = [
   "self-hosted"
 ];
 
+const runsOnValueProvider = {
+  kind: ValueProviderKind.SuggestedValues,
+  get: () => Promise.resolve(stringsToValues(DEFAULT_RUNNER_LABELS))
+};
+
 export const defaultValueProviders: ValueProviderConfig = {
   needs: {
     kind: ValueProviderKind.AllowedValues,
@@ -32,8 +37,6 @@ export const defaultValueProviders: ValueProviderConfig = {
     kind: ValueProviderKind.SuggestedValues,
     get: (context, existingValues) => Promise.resolve(reusableJobSecrets(context, existingValues))
   },
-  "runs-on": {
-    kind: ValueProviderKind.SuggestedValues,
-    get: () => Promise.resolve(stringsToValues(DEFAULT_RUNNER_LABELS))
-  }
+  "runs-on": runsOnValueProvider,
+  "runs-on-labels": runsOnValueProvider
 };