Add test for invalid electron version

src/index.js

@@ -1,9 +1,8 @@
 import browserslist from "browserslist";
 import builtInsList from "../data/built-ins.json";
 import defaultInclude from "./default-includes";
-import { electronToChromium } from "electron-to-chromium";
 import moduleTransformations from "./module-transformations";
-import normalizeOptions from "./normalize-options.js";
+import normalizeOptions, { getElectronChromeVersion } from "./normalize-options.js";
 import pluginList from "../data/plugins.json";
 import transformPolyfillRequirePlugin from "./transform-polyfill-require-plugin";
 
@@ -101,19 +100,13 @@ export const getTargets = (targets = {}) => {
     targetOps.node = getCurrentNodeVersion();
   }
 
-  // Rewrite Electron versions to their Chrome equivalents
+  // Replace Electron target with its Chrome equivalent
   if (targetOps.electron) {
-    const electronChromeVersion = parseInt(electronToChromium(targetOps.electron), 10);
+    const electronChromeVersion = getElectronChromeVersion(targetOps.electron);
 
-    if (!electronChromeVersion) {
-      throw new Error(`Electron version ${targetOps.electron} is either too old or too new`);
-    }
-
-    if (targetOps.chrome) {
-      targetOps.chrome = Math.min(targetOps.chrome, electronChromeVersion);
-    } else {
-      targetOps.chrome = electronChromeVersion;
-    }
+    targetOps.chrome = targetOps.chrome
+      ? Math.min(targetOps.chrome, electronChromeVersion)
+      : electronChromeVersion;
 
     delete targetOps.electron;
   }

src/normalize-options.js

@@ -1,4 +1,5 @@
 import invariant from "invariant";
+import { electronToChromium } from "electron-to-chromium";
 import builtInsList from "../data/built-ins.json";
 import defaultInclude from "./default-includes";
 import moduleTransformations from "./module-transformations";
@@ -69,6 +70,17 @@ export const validateModulesOption = (modulesOpt = "commonjs") => {
   return modulesOpt;
 };
 
+export const getElectronChromeVersion = (electronVersion) => {
+  const electronChromeVersion = parseInt(electronToChromium(electronVersion), 10);
+
+  invariant(
+    !!electronChromeVersion,
+    `Electron version ${electronVersion} is either too old or too new`
+  );
+
+  return electronChromeVersion;
+};
+
 export default function normalizeOptions(opts) {
   // TODO: remove whitelist in favor of include in next major
   if (opts.whitelist && !hasBeenWarned) {

test/index.spec.js

@@ -66,6 +66,23 @@ describe("babel-preset-env", () => {
         });
       });
     });
+
+    it("should error if electron version is invalid", () => {
+      const fixtures = [
+        "0.19",
+        0.19,
+        999,
+        "999",
+      ];
+
+      fixtures.forEach((electronVersion) => {
+        assert.throws(() => {
+          babelPresetEnv.getTargets({
+            electron: electronVersion,
+          });
+        }, Error);
+      });
+    });
   });
 
   describe("isPluginRequired", () => {