feat: allow bare version placeholder to be replaced in customDir (#143)

README.md

@@ -72,6 +72,21 @@ const nightlyZipFilePath = await download('8.0.0-nightly.20190901', {
 // Will download from https://nightly.example.com/nightlies/nightly-linux.zip
 ```
 
+`customDir` can have the placeholder `{{ version }}`, which will be replaced by the version
+specified (without the leading `v`). For example:
+
+```javascript
+const zipFilePath = await download('4.0.4', {
+  mirrorOptions: {
+    mirror: 'https://mirror.example.com/electron/',
+    customDir: 'version-{{ version }}',
+    platform: 'linux',
+    arch: 'x64'
+  }
+});
+// Will download from https://mirror.example.com/electron/version-4.0.4/electron-v4.0.4-linux-x64.zip
+```
+
 ## How It Works
 
 This module downloads Electron to a known place on your system and caches it

src/artifact-utils.ts

@@ -44,7 +44,10 @@ export function getArtifactRemoteURL(details: ElectronArtifactDetails): string {
   if (details.version.includes('nightly')) {
     base = mirrorVar('nightly_mirror', opts, NIGHTLY_BASE_URL);
   }
-  const path = mirrorVar('customDir', opts, details.version);
+  const path = mirrorVar('customDir', opts, details.version).replace(
+    '{{ version }}',
+    details.version.replace(/^v/, ''),
+  );
   const file = mirrorVar('customFilename', opts, getArtifactFileName(details));
 
   return `${base}${path}/${file}`;

test/artifact-utils.spec.ts

@@ -99,6 +99,22 @@ describe('artifact-utils', () => {
       );
     });
 
+    it('should replace {{ version }} when mirrorOptions.customDir is set', () => {
+      expect(
+        getArtifactRemoteURL({
+          arch: 'x64',
+          artifactName: 'electron',
+          mirrorOptions: {
+            customDir: 'foo{{ version }}bar',
+          },
+          platform: 'linux',
+          version: 'v1.2.3',
+        }),
+      ).toMatchInlineSnapshot(
+        `"https://github.com/electron/electron/releases/download/foo1.2.3bar/electron-v1.2.3-linux-x64.zip"`,
+      );
+    });
+
     it('should replace the filename when mirrorOptions.customFilename is set', () => {
       expect(
         getArtifactRemoteURL({