Handle inference where electron-prebuilt-compile points to a non-version

Fixes #975.

src/infer.js

@@ -46,16 +46,24 @@ function resolvePromise (id, options) {
   })
 }
 
+function rangeFromElectronVersion (electronVersion) {
+  try {
+    return new semver.Range(electronVersion)
+  } catch (error) {
+    return null
+  }
+}
+
 async function getVersion (opts, electronProp) {
   const [depType, packageName] = electronProp.prop.split('.')
   const src = electronProp.src
   if (packageName === 'electron-prebuilt-compile') {
-    // electron-prebuilt-compile cannot be resolved because `main` does not point
-    // to a valid JS file.
     const electronVersion = electronProp.pkg[depType][packageName]
-    const versionRange = new semver.Range(electronVersion)
-    if (versionRange.intersects(new semver.Range('< 1.6.5'))) {
+    const versionRange = rangeFromElectronVersion(electronVersion)
+    if (versionRange !== null && versionRange.intersects(new semver.Range('< 1.6.5'))) {
       if (!/^\d+\.\d+\.\d+/.test(electronVersion)) {
+        // electron-prebuilt-compile cannot be resolved because `main` does not point
+        // to a valid JS file.
         throw new Error('Using electron-prebuilt-compile with Electron Packager requires specifying an exact Electron version')
       }
 

test/fixtures/infer-non-version-electron-prebuilt-compile/package.json

@@ -0,0 +1,7 @@
+{
+  "main": "main.js",
+  "productName": "MainJS",
+  "devDependencies": {
+    "electron-prebuilt-compile": "@scoped/electron-prebuilt-compile"
+  }
+}

test/infer.js

@@ -79,6 +79,13 @@ test('infer using `electron-prebuilt` package', util.testSinglePlatform(inferEle
 test('infer using `electron-nightly` package', util.testSinglePlatform(inferElectronVersionTest, 'infer-electron-nightly', 'electron-nightly'))
 test('infer using `electron-prebuilt-compile` package', util.testSinglePlatform(inferElectronVersionTest, 'infer-electron-prebuilt-compile', 'electron-prebuilt-compile'))
 test('infer using non-exact `electron-prebuilt-compile` package', util.testSinglePlatform(inferElectronVersionTest, 'infer-non-specific-electron-prebuilt-compile', 'electron-prebuilt-compile'))
+test('infer when electron-prebuilt-compile dependency points to URL instead of version', util.testSinglePlatform(async (t, opts) => {
+  delete opts.electronVersion
+  opts.dir = util.fixtureSubdir('infer-non-version-electron-prebuilt-compile')
+
+  await getMetadataFromPackageJSON([], opts, opts.dir)
+  t.is(opts.electronVersion, '2.0.10', 'Electron version matches the value in the electron-prebuilt-compile package.json')
+}))
 test('infer using `electron` package only', util.testSinglePlatform(inferMissingVersionTest))
 test('infer where `electron` version is preferred over `electron-prebuilt`', util.testSinglePlatform(inferElectronVersionTest, 'basic-renamed-to-electron', 'electron'))
 test('infer win32metadata', util.testSinglePlatform(async (t, opts) => {