Fetches the latest Cake version number from GitHub

__tests__/cakeRelease.test.ts

@@ -0,0 +1,112 @@
+import * as http from '@actions/http-client';
+import * as cakeRelease from '../src/cakeRelease';
+
+describe('When retrieving the latest Cake version', () => {
+  beforeAll(async () => {
+    jest
+      .spyOn(http.HttpClient.prototype, 'getJson')
+      .mockImplementation(async () => ({
+        statusCode: 200,
+        result: {
+          tag_name: 'v1.0.0'
+        },
+        headers: {}
+      }));
+  });
+
+  test('it should return the latest version number from GitHub', async () => {
+    expect(await cakeRelease.getLatestVersion()).toBe('1.0.0');
+  });
+});
+
+describe('When retrieving the latest Cake version without the \'v\' prefix', () => {
+  beforeAll(async () => {
+    jest
+      .spyOn(http.HttpClient.prototype, 'getJson')
+      .mockImplementation(async () => ({
+        statusCode: 200,
+        result: {
+          tag_name: '1.0.0'
+        },
+        headers: {}
+      }));
+  });
+
+  test('it should return the latest version number from GitHub', async () => {
+    expect(await cakeRelease.getLatestVersion()).toBe('1.0.0');
+  });
+});
+
+describe('When failing to retrieve the latest Cake version due to a GitHub error', () => {
+  beforeAll(async () => {
+    jest
+      .spyOn(http.HttpClient.prototype, 'getJson')
+      .mockImplementation(async () => ({
+        statusCode: 500,
+        result: {},
+        headers: {}
+      }));
+  });
+
+  test('it should return null', async () => {
+    expect(await cakeRelease.getLatestVersion()).toBeNull();
+  });
+
+  test('it should log the fact that the GitHub API returned an error', async () => {
+    const log = jest.spyOn(console, 'log');
+    await cakeRelease.getLatestVersion();
+    expect(log).toHaveBeenCalledWith('Could not determine the latest version of Cake. GitHub returned status code 500');
+  });
+});
+
+describe('When failing to retrieve the latest Cake version due to an empty response from GitHub', () => {
+  beforeAll(async () => {
+    jest
+      .spyOn(http.HttpClient.prototype, 'getJson')
+      .mockImplementation(async () => ({
+        statusCode: 200,
+        result: {},
+        headers: {}
+      }));
+  });
+
+  test('it should return null', async () => {
+    expect(await cakeRelease.getLatestVersion()).toBeNull();
+  });
+});
+
+describe('When failing to retrieve the latest Cake version due to a missing tag name in the GitHub response', () => {
+  beforeAll(async () => {
+    jest
+      .spyOn(http.HttpClient.prototype, 'getJson')
+      .mockImplementation(async () => ({
+        statusCode: 200,
+        result: {
+          tag_name: null
+        },
+        headers: {}
+      }));
+  });
+
+  test('it should return null', async () => {
+    expect(await cakeRelease.getLatestVersion()).toBeNull();
+  });
+});
+
+describe('When failing to retrieve the latest Cake version due to an empty tag name in the GitHub response', () => {
+  beforeAll(async () => {
+    jest
+      .spyOn(http.HttpClient.prototype, 'getJson')
+      .mockImplementation(async () => ({
+        statusCode: 200,
+        result: {
+          tag_name: ''
+        },
+        headers: {}
+      }));
+  });
+
+  test('it should return null', async () => {
+    expect(await cakeRelease.getLatestVersion()).toBeNull();
+  });
+});

package.json

@@ -26,6 +26,7 @@
   "dependencies": {
     "@actions/core": "^1.9.1",
     "@actions/exec": "^1.0.1",
+    "@actions/http-client": "^2.0.1",
     "@actions/io": "^1.0.1"
   },
   "devDependencies": {

src/cakeRelease.ts

@@ -0,0 +1,26 @@
+import * as http from '@actions/http-client';
+
+export async function getLatestVersion(): Promise<string | null> {
+  const release = await getLatestCakeReleaseFromGitHub();
+  return extractVersionNumber(release);
+}
+
+async function getLatestCakeReleaseFromGitHub(): Promise<GitHubRelease | null> {
+  const client = new http.HttpClient('cake-build/cake-action');
+  const response = await client.getJson<GitHubRelease>('https://api.github.com/repos/cake-build/cake/releases/latest');
+
+  if (response.statusCode != 200) {
+    console.log(`Could not determine the latest version of Cake. GitHub returned status code ${response.statusCode}`);
+    return null;
+  }
+
+  return response.result;
+}
+
+function extractVersionNumber(release: GitHubRelease | null): string | null {
+  return release?.tag_name?.replace(/^v/, '') || null;
+}
+
+interface GitHubRelease {
+  tag_name: string;
+}