Add --wasm flag to deploy for Flutter Web WebAssembly builds

CHANGELOG.md

@@ -1 +1,2 @@
 - Support setting the Google Cloud Storage (GCS) test results bucket in `apptesting:execute` and `appdistribution:distribute`
+- Added a `--wasm` flag to `firebase deploy` to compile Flutter Web to WebAssembly when building for Hosting

src/commands/deploy.ts

@@ -102,7 +102,8 @@ export const command = new Command("deploy")
     "--dry-run",
     "perform a dry run of your deployment. Validates your changes and builds your code without deploying any changes to your project. " +
       "In order to provide better validation, this may still enable APIs on the target project",
-  );
+  )
+  .option("--wasm", "compile Flutter Web to WebAssembly when building the framework for Hosting");
 
 if (experiments.isEnabled("apphostinglocalbuilds")) {
   command.option(

src/frameworks/flutter/index.spec.ts

@@ -110,6 +110,30 @@ describe("Flutter", () => {
       });
       sinon.assert.calledWith(stub, "flutter", ["build", "web"], { cwd, stdio: "inherit" });
     });
+
+    it("should pass --wasm when the wasm context is set", async () => {
+      const process = new EventEmitter() as any;
+      process.stdin = new Writable();
+      process.stdout = new EventEmitter();
+      process.stderr = new EventEmitter();
+      process.status = 0;
+
+      sandbox.stub(flutterUtils, "assertFlutterCliExists").returns(undefined);
+
+      const cwd = ".";
+
+      const stub = sandbox.stub(crossSpawn, "sync").returns(process as any);
+
+      const result = build(cwd, undefined, { wasm: true });
+
+      expect(await result).to.deep.equal({
+        wantsBackend: false,
+      });
+      sinon.assert.calledWith(stub, "flutter", ["build", "web", "--wasm"], {
+        cwd,
+        stdio: "inherit",
+      });
+    });
   });
 
   describe("init", () => {

src/frameworks/flutter/index.ts

@@ -2,7 +2,13 @@ import { sync as spawnSync } from "cross-spawn";
 import { copy, pathExists } from "fs-extra";
 import { join } from "path";
 
-import { BuildResult, Discovery, FrameworkType, SupportLevel } from "../interfaces";
+import {
+  BuildResult,
+  Discovery,
+  FrameworkContext,
+  FrameworkType,
+  SupportLevel,
+} from "../interfaces";
 import { FirebaseError } from "../../error";
 import { assertFlutterCliExists, getPubSpec, getAdditionalBuildArgs } from "./utils";
 import { DART_RESERVED_WORDS, FALLBACK_PROJECT_NAME } from "./constants";
@@ -47,12 +53,18 @@ export function init(setup: any, config: any) {
   return Promise.resolve();
 }
 
-export async function build(cwd: string): Promise<BuildResult> {
+export async function build(
+  cwd: string,
+  _target?: string,
+  context?: FrameworkContext,
+): Promise<BuildResult> {
   assertFlutterCliExists();
 
   const pubSpec = await getPubSpec(cwd);
   const otherArgs = getAdditionalBuildArgs(pubSpec);
-  const buildArgs = ["build", "web", ...otherArgs].filter(Boolean);
+  // Compile to WebAssembly when `firebase deploy --wasm` is used.
+  const wasmArgs = context?.wasm ? ["--wasm"] : [];
+  const buildArgs = ["build", "web", ...otherArgs, ...wasmArgs].filter(Boolean);
 
   const build = spawnSync("flutter", buildArgs, { cwd, stdio: "inherit" });
   if (build.status !== 0) throw new FirebaseError("Unable to build your Flutter app");

src/frameworks/index.ts

@@ -297,6 +297,7 @@ export async function prepareFrameworks(
       projectId: project,
       site: options.site,
       hostingChannel: context?.hostingChannel,
+      wasm: options.wasm,
     };
 
     let codegenFunctionsDirectory: Framework["ɵcodegenFunctionsDirectory"];

src/frameworks/interfaces.ts

@@ -46,12 +46,14 @@ export type FrameworksOptions = HostingOptions &
   Options & {
     frameworksDevModeHandle?: RequestHandler;
     nonInteractive?: boolean;
+    wasm?: boolean;
   };
 
 export type FrameworkContext = {
   projectId?: string;
   hostingChannel?: string;
   site?: string;
+  wasm?: boolean;
 };
 
 export interface Framework {