From dcc74252e855abacf5f4c77bf2e06a3469b05654 Mon Sep 17 00:00:00 2001
From: Ivan Trubach <mr.trubach@icloud.com>
Date: Sun, 15 Dec 2019 00:12:27 +0300
Subject: [PATCH] Add support for major release selection

This commit adds 'latest' version alias that resolves to the
latest available release.

The getPossibleVersions function filters available releases using
startsWith(version), so calling getLatestVersion(version) with an
empty string will return the latest release.

Closes #31
---
 __tests__/installer.test.ts | 12 ++++++++++++
 src/installer.ts            |  6 +++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/__tests__/installer.test.ts b/__tests__/installer.test.ts
index fcaa76f..d4160bc 100644
--- a/__tests__/installer.test.ts
+++ b/__tests__/installer.test.ts
@@ -89,6 +89,18 @@ describe('installer tests', () => {
         expect(fs.existsSync(path.join(goDir, 'bin', 'go'))).toBe(true);
       }
     }, 100000);
+
+    it('Acquires latest release version of go if using latest and matching version is installed', async () => {
+      await installer.getGo('latest');
+      const goDir = path.join(toolDir, 'go', '1.13.0', os.arch());
+
+      expect(fs.existsSync(`${goDir}.complete`)).toBe(true);
+      if (IS_WINDOWS) {
+        expect(fs.existsSync(path.join(goDir, 'bin', 'go.exe'))).toBe(true);
+      } else {
+        expect(fs.existsSync(path.join(goDir, 'bin', 'go'))).toBe(true);
+      }
+    }, 100000);
   });
 
   it('Throws if no location contains correct go version', async () => {
diff --git a/src/installer.ts b/src/installer.ts
index 9f25476..199f366 100644
--- a/src/installer.ts
+++ b/src/installer.ts
@@ -167,6 +167,10 @@ function normalizeVersion(version: string): string {
 }
 
 async function determineVersion(version: string): Promise<string> {
+  if (version == 'latest') {
+    return await getLatestVersion('');
+  }
+
   if (!version.endsWith('.x')) {
     const versionPart = version.split('.');
 
@@ -188,7 +192,7 @@ async function getLatestVersion(version: string): Promise<string> {
 
   core.debug(`evaluating ${versions.length} versions`);
 
-  if (version.length === 0) {
+  if (versions.length === 0) {
     throw new Error('unable to get latest version');
   }