Improve cron schedule validation and diagnostics (#224)

languageservice/src/validate.test.ts

@@ -181,7 +181,7 @@ jobs:
 
     expect(result.length).toBe(1);
     expect(result[0]).toEqual({
-      message: "Invalid cron string",
+      message: "Invalid cron expression. Expected format: '* * * * *' (minute hour day month weekday)",
       range: {
         end: {
           character: 21,
@@ -195,6 +195,95 @@ jobs:
     } as Diagnostic);
   });
 
+  it("cron with interval less than 5 minutes shows warning", async () => {
+    const result = await validate(
+      createDocument(
+        "wf.yaml",
+        `on:
+  schedule:
+    - cron: '*/1 * * * *'
+jobs:
+  build:
+    runs-on: ubuntu-latest`
+      ),
+      {valueProviderConfig: defaultValueProviders}
+    );
+
+    expect(result.length).toBe(1);
+    expect(result[0]).toEqual({
+      message: "Runs every minute. Note: Actions schedules run at most every 5 minutes.",
+      severity: DiagnosticSeverity.Warning,
+      code: "on-schedule",
+      codeDescription: {
+        href: "https://docs.github.com/actions/using-workflows/workflow-syntax-for-github-actions#onschedule"
+      },
+      range: {
+        end: {
+          character: 25,
+          line: 2
+        },
+        start: {
+          character: 12,
+          line: 2
+        }
+      }
+    } as Diagnostic);
+  });
+
+  it("cron with interval of 5 minutes or more shows info", async () => {
+    const result = await validate(
+      createDocument(
+        "wf.yaml",
+        `on:
+  schedule:
+    - cron: '*/5 * * * *'
+jobs:
+  build:
+    runs-on: ubuntu-latest`
+      ),
+      {valueProviderConfig: defaultValueProviders}
+    );
+
+    expect(result.length).toBe(1);
+    expect(result[0]).toEqual({
+      message: "Runs every 5 minutes",
+      severity: DiagnosticSeverity.Information,
+      code: "on-schedule",
+      codeDescription: {
+        href: "https://docs.github.com/actions/using-workflows/workflow-syntax-for-github-actions#onschedule"
+      },
+      range: {
+        end: {
+          character: 25,
+          line: 2
+        },
+        start: {
+          character: 12,
+          line: 2
+        }
+      }
+    } as Diagnostic);
+  });
+
+  it("cron with comma-separated minutes less than 5 apart shows warning", async () => {
+    const result = await validate(
+      createDocument(
+        "wf.yaml",
+        `on:
+  schedule:
+    - cron: '0,2 * * * *'
+jobs:
+  build:
+    runs-on: ubuntu-latest`
+      ),
+      {valueProviderConfig: defaultValueProviders}
+    );
+
+    expect(result.length).toBe(1);
+    expect(result[0]?.severity).toBe(DiagnosticSeverity.Warning);
+    expect(result[0]?.message).toContain("Note: Actions schedules run at most every 5 minutes.");
+  });
+
   it("invalid YAML", async () => {
     // This YAML has some mismatched single-quotes, which causes the string to be terminated early
     // within the fromJSON() expression.