feat: grab latest electron version from github if not specified

packages/electron-builder/src/util/readPackageJson.ts

@@ -1,6 +1,8 @@
 import Ajv from "ajv"
+import { CancellationToken } from "electron-builder-http/out/CancellationToken"
 import { debug } from "electron-builder-util"
 import { log, warn } from "electron-builder-util/out/log"
+import { httpExecutor } from "electron-builder-util/out/nodeHttpExecutor"
 import { readFile, readJson } from "fs-extra-p"
 import { safeLoad } from "js-yaml"
 import JSON5 from "json5"
@@ -112,6 +114,20 @@ export async function getElectronVersion(config: Config | null | undefined, proj
   const packageJsonPath = path.join(projectDir, "package.json")
   const electronPrebuiltDep = findFromElectronPrebuilt(projectMetadata || await readJson(packageJsonPath))
   if (electronPrebuiltDep == null) {
+    try {
+      const releaseInfo = await httpExecutor.request<any>({
+        hostname: "github.com",
+        path: "/electron/electron/releases/latest",
+        headers: {
+          Accept: "application/json",
+        },
+      }, new CancellationToken())
+      return (releaseInfo.tag_name.startsWith("v")) ? releaseInfo.tag_name.substring(1) : releaseInfo.tag_name
+    }
+    catch (e) {
+      warn(e)
+    }
+
     throw new Error(`Cannot find electron dependency to get electron version in the '${packageJsonPath}'`)
   }
 

test/out/__snapshots__/ExtraBuildTest.js.snap

@@ -79,6 +79,12 @@ Object {
 }
 `;
 
+exports[`retrieve latest electron version 1`] = `
+Object {
+  "linux": Array [],
+}
+`;
+
 exports[`scheme validation 1`] = `
 "Config is invalid:
 {

test/src/ExtraBuildTest.ts

@@ -4,7 +4,7 @@ import { move, readFile } from "fs-extra-p"
 import { safeLoad } from "js-yaml"
 import * as path from "path"
 import { assertThat } from "./helpers/fileAssert"
-import { app, appThrows, assertPack } from "./helpers/packTester"
+import { app, appThrows, assertPack, modifyPackageJson } from "./helpers/packTester"
 import { expectUpdateMetadata } from "./helpers/winHelper"
 
 function createBuildResourcesTest(platform: Platform) {
@@ -56,6 +56,14 @@ test.ifAll.ifLinuxOrDevMac("prepackaged", app({
   }
 }))
 
+test.ifAll.ifLinuxOrDevMac("retrieve latest electron version", app({
+  targets: linuxDirTarget,
+}, {
+  projectDirCreated: projectDir => modifyPackageJson(projectDir, data => {
+    delete data.build.electronVersion
+  }),
+}))
+
 test.ifAll.ifDevOrLinuxCi("override targets in the config", app({
   targets: linuxDirTarget,
 }, {