test: added more flow type checks

src/cmd/build.js

@@ -12,10 +12,43 @@ import {createLogger} from '../util/logger';
 
 const log = createLogger(__filename);
 
+// Flow Types
 
-async function defaultPackageCreator(
-    {manifestData, sourceDir, fileFilter, artifactsDir}) {
+import type {OnSourceChangeFn} from '../watcher';
+import type {ExtensionManifest} from '../util/manifest';
+
+export type PackageCreatorFn =
+    (params: PackageCreatorParams) => Promise<ExtensionBuildResult>;
+
+export type ExtensionBuildResult = {
+  extensionPath: string,
+};
+
+export type PackageCreatorParams = {
+  manifestData?: ExtensionManifest,
+  sourceDir: string,
+  fileFilter: FileFilter,
+  artifactsDir: string,
+};
+
+export type BuildCmdParams = {
+  sourceDir: string,
+  artifactsDir: string,
+  asNeeded?: boolean,
+};
 
+export type BuildCmdExtraParams = {
+  manifestData?: ExtensionManifest,
+  fileFilter?: FileFilter,
+  onSourceChange?: OnSourceChangeFn,
+  packageCreator?: PackageCreatorFn,
+};
+
+// Private Helpers
+
+async function defaultPackageCreator(
+  {manifestData, sourceDir, fileFilter, artifactsDir}: PackageCreatorParams
+): Promise<ExtensionBuildResult> {
   manifestData = await new Promise(
     (resolve) => {
       if (manifestData) {
@@ -44,14 +77,16 @@ async function defaultPackageCreator(
   return {extensionPath};
 }
 
+// Exports
 
 export default async function build(
-    {sourceDir, artifactsDir, asNeeded=false}: Object,
-    {manifestData, fileFilter=new FileFilter(),
-     onSourceChange=defaultSourceWatcher,
-     packageCreator=defaultPackageCreator}
-    : Object = {}): Promise {
-
+  {sourceDir, artifactsDir, asNeeded=false}: BuildCmdParams,
+  {
+    manifestData, fileFilter=new FileFilter(),
+    onSourceChange=defaultSourceWatcher,
+    packageCreator=defaultPackageCreator,
+  }: BuildCmdExtraParams = {}
+): Promise<ExtensionBuildResult> {
   const rebuildAsNeeded = asNeeded; // alias for `build --as-needed`
   log.info(`Building web extension from ${sourceDir}`);
 

src/util/manifest.js

@@ -8,6 +8,15 @@ import {createLogger} from './logger';
 const log = createLogger(__filename);
 
 
+// Flow Types
+
+export type ExtensionManifest = {
+  name: string,
+  version: string,
+};
+
+// Exports
+
 export default async function getValidatedManifest(sourceDir: string): Promise {
   let manifestFile = path.join(sourceDir, 'manifest.json');
   log.debug(`Validating manifest at ${manifestFile}`);

src/watcher.js

@@ -8,8 +8,38 @@ import {FileFilter} from './cmd/build';
 const log = createLogger(__filename);
 
 
+// Flow Types
+
+export type ShouldWatchFn = (filePath: string) => boolean;
+
+export type OnChangeFn = () => any;
+
+export type OnSourceChangeParams = {
+  sourceDir: string,
+  artifactsDir: string,
+  onChange: OnChangeFn,
+  shouldWatchFile?: ShouldWatchFn,
+};
+
+export type ProxyFileChangesParams = {
+  artifactsDir: string,
+  onChange: OnChangeFn,
+  filePath: string,
+  shouldWatchFile?: ShouldWatchFn,
+};
+
+export type OnSourceChangeFn = (params: OnSourceChangeParams) => Watchpack;
+
+// NOTE: this fix an issue with flow and default exports (which currently
+// lose their type signatures) by explicitly declare the default export
+// signature. Reference: https://github.com/facebook/flow/issues/449
+declare function exports(params: OnSourceChangeParams): Watchpack; // eslint-disable-line no-unused-vars
+
+// Exports
+
 export default function onSourceChange(
-    {sourceDir, artifactsDir, onChange, shouldWatchFile}: Object): Watchpack {
+  {sourceDir, artifactsDir, onChange, shouldWatchFile}: OnSourceChangeParams
+): Watchpack {
   // TODO: For network disks, we would need to add {poll: true}.
   const watcher = new Watchpack();
 
@@ -29,9 +59,9 @@ export default function onSourceChange(
   return watcher;
 }
 
-
 export function proxyFileChanges(
-    {artifactsDir, onChange, filePath, shouldWatchFile}: Object) {
+  {artifactsDir, onChange, filePath, shouldWatchFile}: ProxyFileChangesParams
+) {
   if (!shouldWatchFile) {
     const fileFilter = new FileFilter();
     shouldWatchFile = (...args) => fileFilter.wantFile(...args);