Add go-version-from-file option

__tests__/setup-go.test.ts

@@ -31,6 +31,7 @@ describe('setup-go', () => {
   let dbgSpy: jest.SpyInstance;
   let whichSpy: jest.SpyInstance;
   let existsSpy: jest.SpyInstance;
+  let readFileSpy: jest.SpyInstance;
   let mkdirpSpy: jest.SpyInstance;
   let execSpy: jest.SpyInstance;
   let getManifestSpy: jest.SpyInstance;
@@ -60,6 +61,7 @@ describe('setup-go', () => {
     // io
     whichSpy = jest.spyOn(io, 'which');
     existsSpy = jest.spyOn(fs, 'existsSync');
+    readFileSpy = jest.spyOn(fs, 'readFileSync');
     mkdirpSpy = jest.spyOn(io, 'mkdirP');
 
     // gets
@@ -556,4 +558,43 @@ describe('setup-go', () => {
   it('does not convert exact versions', async () => {
     expect(im.makeSemver('1.13.1')).toBe('1.13.1');
   });
+
+  describe('go-version-from-file', () => {
+    it('reads version from file', async () => {
+      inputs['go-version-from-file'] = '.go-version';
+      readFileSpy.mockImplementation(() => Buffer.from(`1.13.0${osm.EOL}`));
+
+      await main.run();
+
+      expect(logSpy).toHaveBeenCalledWith(
+        'Setup go stable version spec 1.13.0'
+      );
+    });
+
+    it('is overwritten by go-version', async () => {
+      inputs['go-version'] = '1.13.1';
+
+      inputs['go-version-from-file'] = '.go-version';
+      readFileSpy.mockImplementation(() => Buffer.from(`1.13.0${osm.EOL}`));
+
+      await main.run();
+
+      expect(logSpy).toHaveBeenCalledWith(
+        'Setup go stable version spec 1.13.1'
+      );
+    });
+
+    it('reports a read failure', async () => {
+      const versionFilePath = '.go-version';
+      inputs['go-version-from-file'] = versionFilePath;
+      const errMsg = `ENOENT: no such file or directory, open '${versionFilePath}'`;
+      readFileSpy.mockImplementation(() => {
+        throw new Error(errMsg);
+      });
+
+      await main.run();
+
+      expect(cnSpy).toHaveBeenCalledWith(`::error::${errMsg}${osm.EOL}`);
+    });
+  });
 });

action.yml

@@ -4,6 +4,8 @@ author: 'GitHub'
 inputs: 
   go-version:
     description: 'The Go version to download (if necessary) and use. Supports semver spec and ranges.'
+  go-version-from-file:
+    description: Path to the file with the Go version.  go-version overwrites this.
   stable:
     description: 'Whether to download only stable versions'
     default: 'true'

dist/index.js

@@ -1432,7 +1432,13 @@ function run() {
             // versionSpec is optional.  If supplied, install / use from the tool cache
             // If not supplied then problem matchers will still be setup.  Useful for self-hosted.
             //
-            let versionSpec = core.getInput('go-version');
+            const versionFilePath = core.getInput('go-version-from-file');
+            const versionSpecFromFile = versionFilePath &&
+                fs_1.default
+                    .readFileSync(versionFilePath)
+                    .toString()
+                    .trim();
+            let versionSpec = core.getInput('go-version') || versionSpecFromFile;
             // stable will be true unless false is the exact input
             // since getting unstable versions should be explicit
             let stable = (core.getInput('stable') || 'true').toUpperCase() === 'TRUE';

src/main.ts

@@ -12,7 +12,14 @@ export async function run() {
     // versionSpec is optional.  If supplied, install / use from the tool cache
     // If not supplied then problem matchers will still be setup.  Useful for self-hosted.
     //
-    let versionSpec = core.getInput('go-version');
+    const versionFilePath = core.getInput('go-version-from-file');
+    const versionSpecFromFile =
+      versionFilePath &&
+      fs
+        .readFileSync(versionFilePath)
+        .toString()
+        .trim();
+    let versionSpec = core.getInput('go-version') || versionSpecFromFile;
 
     // stable will be true unless false is the exact input
     // since getting unstable versions should be explicit