Better flow coverage

.flowconfig

@@ -10,4 +10,4 @@ include_warnings=true
 suppress_comment= \\(.\\|\n\\)*\\$FlowIgnore
 suppress_type=$FlowIgnore
 esproposal.optional_chaining=enable
-module.name_mapper='^@babel\/plugin-inject-polyfills$' -> '<PROJECT_ROOT>/packages/babel-plugin-inject-polyfills/src/index'
+module.name_mapper='^@babel/plugin-inject-polyfills$' -> '<PROJECT_ROOT>/packages/babel-plugin-inject-polyfills/src/index'

packages/babel-plugin-inject-polyfills/src/define-provider.js

@@ -0,0 +1,11 @@
+// @flow
+
+import type { PolyfillProviderInternal, PolyfillProvider } from "./types";
+
+export function defineProvider<Options>(
+  factory: PolyfillProvider<Options>,
+): PolyfillProviderInternal<Options> {
+  // This will allow us to do some things
+
+  return (factory: any);
+}

packages/babel-plugin-inject-polyfills/src/index.js

@@ -23,19 +23,13 @@ import {
 } from "./debug-utils";
 import { validateIncludeExclude } from "./normalize-options";
 
-import type {
-  ProviderApi,
-  Options,
-  Targets,
-  MetaDescriptor,
-  PolyfillProvider,
-  Utils,
-} from "./types";
+import type { ProviderApi, Options, Targets, MetaDescriptor } from "./types";
 
 import createMetaResolver from "./meta-resolver";
 
+export { defineProvider } from "./define-provider";
 export { resolveProvider } from "./config";
-export type { PolyfillProvider, MetaDescriptor, Utils };
+export type { PolyfillProvider, MetaDescriptor, Utils, Targets } from "./types";
 
 export default declare((api, options: Options, dirname: string) => {
   api.assertVersion(7);

packages/babel-plugin-inject-polyfills/src/types.js

@@ -29,6 +29,8 @@ export type PolyfillProvider<Opts = {||}> = (
   dirname: string,
 ) => ProviderResult;
 
+export opaque type PolyfillProviderInternal<Opts> = PolyfillProvider<Opts>;
+
 export type MethodString = "entry-global" | "usage-global" | "usage-pure";
 
 export type Targets = {

packages/babel-polyfill-provider-corejs2/src/add-platform-specific-polyfills.js

@@ -1,3 +1,7 @@
+// @flow
+
+import type { Targets } from "@babel/plugin-inject-polyfills";
+
 const webPolyfills = {
   "web.timers": {},
   "web.immediate": {},
@@ -10,7 +14,7 @@ const purePolyfills = {
   "es7.string.at": {},
 };
 
-export default function(targets, method, polyfills) {
+export default function(targets: Targets, method: string, polyfills: Object) {
   const targetNames = Object.keys(targets);
   const isAnyTarget = !targetNames.length;
   const isWebTarget = targetNames.some(name => name !== "node");

packages/babel-polyfill-provider-corejs2/src/index.js

@@ -10,7 +10,7 @@ import {
 import addPlatformSpecificPolyfills from "./add-platform-specific-polyfills";
 import { hasMinVersion } from "./helpers";
 
-import type { PolyfillProvider } from "@babel/plugin-inject-polyfills";
+import { defineProvider } from "@babel/plugin-inject-polyfills";
 import { types as t } from "@babel/core";
 
 const presetEnvCompat: "#__secret_key__@babel/preset-env__compatibility" =
@@ -26,13 +26,13 @@ type Options = {|
   },
 |};
 
-export default ((
+export default defineProvider<Options>(function(
   api,
   {
     version: runtimeVersion = "7.0.0-beta.0",
     [presetEnvCompat]: { entryInjectRegenerator } = {},
   },
-) => {
+) {
   const resolve = api.createMetaResolver({
     global: BuiltIns,
     static: StaticProperties,
@@ -50,7 +50,7 @@ export default ((
   const coreJSBase =
     method === "usage-pure" ? "core-js/library/fn" : "core-js/modules";
 
-  function inject(name, utils) {
+  function inject(name: string | string[], utils) {
     if (typeof name === "string") {
       if (shouldInjectPolyfill(name)) {
         debug(name);
@@ -185,4 +185,4 @@ export default ((
       },
     },
   };
-}: PolyfillProvider<Options>);
+});

packages/babel-polyfill-provider-corejs3/src/index.js

@@ -16,18 +16,18 @@ import {
 import { types as t } from "@babel/core";
 import { callMethod, coreJSModule, isCoreJSSource } from "./utils";
 
-import { type PolyfillProvider } from "@babel/plugin-inject-polyfills";
+import { defineProvider } from "@babel/plugin-inject-polyfills";
 
 type Options = {|
   version?: number | string,
   proposals?: boolean,
   shippedProposals?: boolean,
 |};
 
-export default ((
+export default defineProvider<Options>(function(
   { getUtils, method, shouldInjectPolyfill, createMetaResolver, debug },
   { version = 3, proposals, shippedProposals },
-) => {
+) {
   const resolve = createMetaResolver({
     global: BuiltIns,
     static: StaticProperties,
@@ -254,4 +254,4 @@ export default ((
       },
     },
   };
-}: PolyfillProvider<Options>);
+});

packages/babel-polyfill-provider-es-shims/src/index.js

@@ -1,6 +1,7 @@
 // @flow
 
-import type { PolyfillProvider, Utils } from "@babel/plugin-inject-polyfills";
+import { defineProvider, type Utils } from "@babel/plugin-inject-polyfills";
+
 import resolve from "resolve";
 import debounce from "lodash.debounce";
 
@@ -13,11 +14,19 @@ import {
   InstanceProperties,
 } from "./mappings";
 
-export default ((
+type Options = {|
+  missingDependencies?: {
+    log?: "per-file" | "deferred",
+    // When true, log all the polyfills without checking if they are installed
+    all?: boolean,
+  },
+|};
+
+export default defineProvider<Options>(function(
   { shouldInjectPolyfill, createMetaResolver, debug },
   options,
   dirname,
-) => {
+) {
   const resolvePolyfill = createMetaResolver<Descriptor[]>({
     global: Globals,
     static: StaticProperties,
@@ -86,7 +95,7 @@ export default ((
       }
     },
   };
-}: PolyfillProvider<*>);
+});
 
 function hasDependency(basedir, name) {
   try {