Add comment on failure

README.md

@@ -65,6 +65,17 @@ To force an API call, set the `GITHUB_TOKEN` environment variable like so:
     labels: "do not merge"
 ```
 
+### Post a comment when the check fails
+
+```yaml
+- uses: mheap/github-action-required-labels@v2
+  with:
+    mode: exactly
+    count: 1
+    labels: "semver:patch, semver:minor, semver:major"
+    add_comment: true
+```
+
 ### Require multiple labels
 
 ```yaml

action.yml

@@ -16,6 +16,10 @@ inputs:
   count:
     description: "The required number of labels to match"
     required: true
+  comment:
+    description: "Add a comment to the PR if required labels are missing"
+    default: "false"
+    required: false
   exit_type:
     description: "The exit type of the action. One of: failure, success, neutral"
     required: false

index.js

@@ -55,8 +55,9 @@ Toolkit.run(async (tools) => {
   let intersection = allowedLabels.filter((x) => appliedLabels.includes(x));
 
   if (mode === "exactly" && intersection.length !== count) {
-    tools.outputs.status = "failure";
-    tools.exit[exitType](
+    await exitWithError(
+      tools,
+      exitType,
       `Label error. Requires exactly ${count} of: ${allowedLabels.join(
         ", "
       )}. Found: ${appliedLabels.join(", ")}`
@@ -65,8 +66,9 @@ Toolkit.run(async (tools) => {
   }
 
   if (mode === "minimum" && intersection.length < count) {
-    tools.outputs.status = "failure";
-    tools.exit[exitType](
+    await exitWithError(
+      tools,
+      exitType,
       `Label error. Requires at least ${count} of: ${allowedLabels.join(
         ", "
       )}. Found: ${appliedLabels.join(", ")}`
@@ -75,8 +77,9 @@ Toolkit.run(async (tools) => {
   }
 
   if (mode === "maximum" && intersection.length > count) {
-    tools.outputs.status = "failure";
-    tools.exit[exitType](
+    await exitWithError(
+      tools,
+      exitType,
       `Label error. Requires at most ${count} of: ${allowedLabels.join(
         ", "
       )}. Found: ${appliedLabels.join(", ")}`
@@ -87,3 +90,20 @@ Toolkit.run(async (tools) => {
   tools.outputs.status = "success";
   tools.exit.success("Complete");
 });
+
+async function exitWithError(tools, exitType, message) {
+  if (tools.inputs.add_comment) {
+    if (process.env.GITHUB_TOKEN) {
+      await tools.github.issues.createComment({
+        ...tools.context.issue,
+        body: message,
+      });
+    } else {
+      throw new Error(
+        "The GITHUB_TOKEN environment variable must be set to add a comment"
+      );
+    }
+  }
+  tools.outputs.status = "failure";
+  tools.exit[exitType](message);
+}

index.test.js

@@ -1,6 +1,8 @@
 const { Toolkit } = require("actions-toolkit");
 const core = require("@actions/core");
 const mockedEnv = require("mocked-env");
+const nock = require("nock");
+nock.disableNetConnect();
 
 describe("Required Labels", () => {
   let action, tools;
@@ -44,6 +46,82 @@ describe("Required Labels", () => {
     restore();
     restoreTest();
     jest.resetModules();
+
+    if (!nock.isDone()) {
+      throw new Error(
+        `Not all nock interceptors were used: ${JSON.stringify(
+          nock.pendingMocks()
+        )}`
+      );
+    }
+    nock.cleanAll();
+  });
+
+  describe("interacts with the API", () => {
+    it("fetches the labels from the API", async () => {
+      restoreTest = mockPr(tools, [], {
+        INPUT_LABELS: "enhancement",
+        INPUT_MODE: "exactly",
+        INPUT_COUNT: "1",
+        GITHUB_TOKEN: "mock-token-here-abc",
+      });
+
+      nock("https://api.github.com")
+        .get("/repos/mheap/missing-repo/issues/28/labels")
+        .reply(200, [{ name: "enhancement" }, { name: "bug" }]);
+
+      await action(tools);
+      expect(core.setOutput).toBeCalledTimes(1);
+      expect(core.setOutput).toBeCalledWith("status", "success");
+      expect(tools.exit.success).toBeCalledTimes(1);
+      expect(tools.exit.success).toBeCalledWith("Complete");
+    });
+
+    it("fetches the labels from the API (and fails)", async () => {
+      restoreTest = mockPr(tools, ["enhancement"], {
+        INPUT_LABELS: "enhancement",
+        INPUT_MODE: "exactly",
+        INPUT_COUNT: "1",
+        GITHUB_TOKEN: "mock-token-here-abc",
+      });
+
+      nock("https://api.github.com")
+        .get("/repos/mheap/missing-repo/issues/28/labels")
+        .reply(200, [{ name: "bug" }]);
+
+      await action(tools);
+      expect(core.setOutput).toBeCalledTimes(1);
+      expect(core.setOutput).toBeCalledWith("status", "failure");
+      expect(tools.exit.failure).toBeCalledTimes(1);
+      expect(tools.exit.failure).toBeCalledWith(
+        "Label error. Requires exactly 1 of: enhancement. Found: bug"
+      );
+    });
+
+    it("posts a comment when enabled", async () => {
+      restoreTest = mockPr(tools, ["enhancement"], {
+        INPUT_LABELS: "enhancement",
+        INPUT_MODE: "exactly",
+        INPUT_COUNT: "1",
+        INPUT_ADD_COMMENT: "true",
+        GITHUB_TOKEN: "mock-token-here-abc",
+      });
+
+      nock("https://api.github.com")
+        .get("/repos/mheap/missing-repo/issues/28/labels")
+        .reply(200, [{ name: "bug" }]);
+
+      nock("https://api.github.com")
+        .post("/repos/mheap/missing-repo/issues/28/comments", {
+          body: "Label error. Requires exactly 1 of: enhancement. Found: bug",
+        })
+        .reply(201);
+
+      await action(tools);
+      expect(tools.exit.failure).toBeCalledWith(
+        "Label error. Requires exactly 1 of: enhancement. Found: bug"
+      );
+    });
   });
 
   describe("success", () => {

package.json

@@ -15,6 +15,7 @@
   },
   "devDependencies": {
     "jest": "^28.1.1",
+    "nock": "^13.2.9",
     "prettier": "^2.7.1"
   },
   "license": "MIT"