add rudimentary .tool-versions parser

.github/workflows/versions.yml

@@ -134,6 +134,22 @@ jobs:
         run: __tests__/verify-go.sh 1.19
         shell: bash
 
+  tool-versions-file:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ ubuntu-latest, windows-latest, macos-latest ]
+    steps:
+      - uses: actions/checkout@v3
+      - name: Setup Go and check latest
+        uses: ./
+        with:
+          tool-versions-file: __tests__/data/.tool-versions
+      - name: verify go
+        run: __tests__/verify-go.sh 1.16.3
+        shell: bash
+
   setup-versions-from-manifest:
     name: Setup ${{ matrix.go }} ${{ matrix.os }}
     runs-on: ${{ matrix.os }}

__tests__/data/.tool-versions

@@ -0,0 +1,4 @@
+terraform 1.3.7
+golang 1.16.3
+python 3.10.11
+ruby 3.2.1

__tests__/setup-go.test.ts

@@ -523,7 +523,8 @@ describe('setup-go', () => {
       return '/Users/testuser/go';
     });
 
-    mkdirpSpy.mockImplementation(async () => {});
+    mkdirpSpy.mockImplementation(async () => {
+    });
     existsSpy.mockImplementation(() => {
       return false;
     });
@@ -957,4 +958,48 @@ use .
         }
     );
   });
+
+  describe('tool-versions-file', () => {
+    const toolVersionsFile = `terraform 1.3.7
+golang 1.16.3
+python 3.10.11
+ruby 3.2.1
+`;
+
+    it('reads version from .tool-versions when specified', async () => {
+      inputs['tool-versions-file'] = '.special-tool-versions'
+      existsSpy.mockImplementation(() => true);
+      readFileSpy.mockImplementation(() => Buffer.from(toolVersionsFile))
+
+      await main.run();
+
+      expect(logSpy).toHaveBeenCalledWith('Setup go version spec 1.16.3');
+      expect(logSpy).toHaveBeenCalledWith('Attempting to download 1.16.3...');
+      expect(logSpy).toHaveBeenCalledWith('matching 1.16.3...');
+    });
+
+    it('is overwritten by go-version param', async () => {
+      inputs['go-version'] = '1.18.2'
+      inputs['tool-versions-file'] = '.special-tool-versions'
+      existsSpy.mockImplementation(() => true);
+      readFileSpy.mockImplementation(() => Buffer.from(toolVersionsFile))
+
+      await main.run();
+
+      expect(logSpy).toHaveBeenCalledWith('Setup go version spec 1.18.2');
+      expect(logSpy).toHaveBeenCalledWith('Attempting to download 1.18.2...');
+      expect(logSpy).toHaveBeenCalledWith('matching 1.18.2...');
+    });
+
+    it('uses .tool-versions as a default when no version specified', async () => {
+      existsSpy.mockImplementation(() => true);
+      readFileSpy.mockImplementation(() => Buffer.from(toolVersionsFile))
+
+      await main.run();
+
+      expect(logSpy).toHaveBeenCalledWith('Setup go version spec 1.16.3');
+      expect(logSpy).toHaveBeenCalledWith('Attempting to download 1.16.3...');
+      expect(logSpy).toHaveBeenCalledWith('matching 1.16.3...');
+    });
+  });
 });

src/installer.ts

@@ -366,6 +366,13 @@ export function parseGoVersionFile(versionFilePath: string): string {
   return contents.trim();
 }
 
+export function parseToolVersionsFile(toolVersionsPath: string): string {
+  const contents = fs.readFileSync(toolVersionsPath).toString();
+
+  const match = contents.match(/^golang (\d+(\.\d+)*)/m);
+  return match ? match[1] : '';
+}
+
 async function resolveStableVersionDist(versionSpec: string, arch: string) {
   const archFilter = sys.getArch(arch);
   const platFilter = sys.getPlatform();

src/main.ts

@@ -138,24 +138,41 @@ export function parseGoVersion(versionString: string): string {
 function resolveVersionInput(): string {
   let version = core.getInput('go-version');
   const versionFilePath = core.getInput('go-version-file');
+  let toolVersionsPath = core.getInput('tool-versions-file');
 
-  if (version && versionFilePath) {
+  if (version && (versionFilePath || toolVersionsPath)) {
     core.warning(
-      'Both go-version and go-version-file inputs are specified, only go-version will be used'
+      'Multiple version inputs are specified, only go-version will be used'
     );
   }
 
   if (version) {
     return version;
-  }
-
-  if (versionFilePath) {
+  } else if (versionFilePath) {
     if (!fs.existsSync(versionFilePath)) {
       throw new Error(
         `The specified go version file at: ${versionFilePath} does not exist`
       );
     }
     version = installer.parseGoVersionFile(versionFilePath);
+  } else {
+    // in the case of no version specification, reach for .tool-versions
+    if(toolVersionsPath && !fs.existsSync(toolVersionsPath)) {
+      throw new Error(
+          `The specified .tool-versions file at ${toolVersionsPath} does not exist`
+      )
+    }
+
+    if (!toolVersionsPath) {
+      toolVersionsPath = '.tool-versions'
+      if(!fs.existsSync(toolVersionsPath)) {
+        throw new Error(
+            `No .tool-versions file was found in the project path. Please specify using tool-versions-file`
+        )
+      }
+    }
+
+    version = installer.parseToolVersionsFile(toolVersionsPath)
   }
 
   return version;