Re-land PR #139 after accidental patch release.

This reverts commit 4b46bb2.

packages/ts-invariant/process/module.d.ts

@@ -0,0 +1,2 @@
+export declare function install(): void;
+export declare function remove(): void;

packages/ts-invariant/process/module.js

@@ -0,0 +1,37 @@
+function maybe(thunk) {
+  try { return thunk() } catch (_) {}
+}
+
+let needToRemove = false;
+
+export function install() {
+  if (!maybe(() => process.env.NODE_ENV) &&
+      !maybe(() => process)) {
+    Object.defineProperty(global, "process", {
+      value: {
+        env: {
+          // This default needs to be "production" instead of "development", to
+          // avoid the problem https://github.com/graphql/graphql-js/pull/2894
+          // will eventually solve, once merged and released.
+          NODE_ENV: "production",
+        },
+      },
+      // Let anyone else change global.process as they see fit, but hide it from
+      // Object.keys(global) enumeration.
+      configurable: true,
+      enumerable: false,
+      writable: true,
+    });
+    needToRemove = true;
+  }
+}
+
+// Call install() at least once, when this module is imported.
+install();
+
+export function remove() {
+  if (needToRemove) {
+    delete global.process;
+    needToRemove = false;
+  }
+}

packages/ts-invariant/process/package.json

@@ -0,0 +1,10 @@
+{
+  "name": "ts-invariant/process",
+  "main": "./main.js",
+  "module": "./module.js",
+  "types": "./module.d.ts",
+  "sideEffects": [
+    "./module.js",
+    "./index.js"
+  ]
+}

packages/ts-invariant/rollup.config.js

@@ -11,7 +11,10 @@ function external(id) {
   return id in globals;
 }
 
-export default [{
+const jobs = [];
+export default jobs;
+
+jobs.push({
   input: "src/invariant.ts",
   external,
   output: {
@@ -26,7 +29,9 @@ export default [{
       tsconfig: "./tsconfig.rollup.json",
     }),
   ],
-}, {
+});
+
+jobs.push({
   input: "lib/invariant.esm.js",
   external,
   output: {
@@ -38,4 +43,17 @@ export default [{
     name: "ts-invariant",
     globals,
   },
-}];
+});
+
+jobs.push({
+  input: "process/module.js",
+  external,
+  output: {
+    file: "process/main.js",
+    format: "cjs",
+    exports: "named",
+    sourcemap: true,
+    name: "ts-invariant/process",
+    globals,
+  },
+});

packages/ts-invariant/src/invariant.ts

@@ -53,20 +53,4 @@ export function setVerbosity(level: VerbosityLevel): VerbosityLevel {
   return old;
 }
 
-// Code that uses ts-invariant with rollup-plugin-invariant may want to
-// import this process stub to avoid errors evaluating process.env.NODE_ENV.
-// However, because most ESM-to-CJS compilers will rewrite the process import
-// as tsInvariant.process, which prevents proper replacement by minifiers, we
-// also export processStub, so you can import { invariant, processStub } from
-// "ts-invariant" and assign processStub to a local variable named process.
-export const processStub: {
-  env: Record<string, any>;
-  [key: string]: any;
-} = (
-  typeof process === "object" &&
-  typeof process.env === "object"
-) ? process : { env: {} };
-
-export { processStub as process };
-
 export default invariant;

packages/ts-invariant/src/tests.ts

@@ -3,11 +3,11 @@ import defaultExport, {
   invariant,
   InvariantError,
   setVerbosity,
-  process,
-  processStub,
 } from "./invariant";
 import reactInvariant from "invariant";
 
+import { install, remove } from "../process";
+
 describe("ts-invariant", function () {
   it("should support both named and default exports", function () {
     assert.strictEqual(defaultExport, invariant);
@@ -145,28 +145,33 @@ describe("ts-invariant", function () {
     checkConsoleMethod("error", true);
   });
 
-  it("should export a usable process polyfill", function () {
-    assert.strictEqual(typeof process, "object");
-    assert.strictEqual(typeof process.env, "object");
-    if (process.versions) {
-      assert.strictEqual(typeof process.versions.node, "string");
-    }
-  });
-
-  it("should export a usable processStub", function () {
-    const process = processStub;
-    assert.strictEqual(typeof process, "object");
-    assert.strictEqual(typeof process.env, "object");
-    if (process.versions) {
-      assert.strictEqual(typeof process.versions.node, "string");
-    }
-  });
-
   it("should let TypeScript know about the assertion made", function () {
     const value: { foo?: { bar?: string } } = {foo: {bar: "bar"}};
     invariant(value.foo, 'fail');
 
      // On compile time this should not raise "TS2532: Object is possibly 'undefined'."
     assert.strictEqual(value.foo.bar, "bar");
   });
+
+  describe("ts-invariant/process", function () {
+    it("install and remove", function () {
+      const origDesc = Object.getOwnPropertyDescriptor(global, "process");
+      Object.defineProperty(global, "process", {
+        value: void 0,
+        configurable: true,
+      });
+      assert.strictEqual(process, void 0);
+      install();
+      assert.deepStrictEqual(process, {
+        env: {
+          NODE_ENV: "production",
+        },
+      });
+      remove();
+      assert.strictEqual(typeof process, "undefined");
+      if (origDesc) {
+        Object.defineProperty(global, "process", origDesc);
+      }
+    });
+  });
 });

tsconfig.json

@@ -5,7 +5,7 @@
     "importHelpers": true,
     "declaration": true,
     "sourceMap": true,
-    "lib": ["es2015"],
+    "lib": ["es2015", "DOM"],
     "types": ["node", "mocha"],
     "strict": true,
     "noImplicitAny": true,