Support both default esmodule and direct commonjs require

__tests__/__fixtures__/flow-package/commonjs.js

@@ -1,6 +1,6 @@
 /* @flow */
 
-var nullthrows = require('../../..').default;
+var nullthrows = require('../../..');
 
 var obj = ({}: ?Object);
 

__tests__/nullthrows-test.js

@@ -1,36 +1,78 @@
 'use strict';
 
-const nullthrows = require('../').default;
+describe('commonjs', () => {
+  const nullthrows = require('../');
 
-test('return value', () => {
-  const obj = {};
-  expect(nullthrows(obj)).toBe(obj);
-});
+  test('return value', () => {
+    const obj = {};
+    expect(nullthrows(obj)).toBe(obj);
+  });
+
+  test('it does not throw', () => {
+    expect(() => {
+      nullthrows('');
+    }).not.toThrow();
+
+    expect(() => {
+      nullthrows(NaN);
+    }).not.toThrow();
 
-test('it does not throw', () => {
-  expect(() => {
-    nullthrows('');
-  }).not.toThrow();
+    expect(() => {
+      nullthrows(false);
+    }).not.toThrow();
+  });
 
-  expect(() => {
-    nullthrows(NaN);
-  }).not.toThrow();
+  test('it throws', () => {
+    expect(() => {
+      nullthrows(null);
+    }).toThrow(new Error('Got unexpected null'));
 
-  expect(() => {
-    nullthrows(false);
-  }).not.toThrow();
+    expect(() => {
+      nullthrows(undefined);
+    }).toThrow(new Error('Got unexpected undefined'));
+
+    expect(() => {
+      nullthrows(undefined, 'My error message');
+    }).toThrow(new Error('My error message'));
+  });
 });
 
-test('it throws', () => {
-  expect(() => {
-    nullthrows(null);
-  }).toThrow(new Error('Got unexpected null'));
+describe('import interop', () => {
+  const interopRequireDefault =
+    require('@babel/runtime-corejs2/helpers/interopRequireDefault.js');
+
+  const nullthrows = interopRequireDefault(require('../'));
+
+  test('return value', () => {
+    const obj = {};
+    expect(nullthrows(obj)).toBe(obj);
+  });
+
+  test('it does not throw', () => {
+    expect(() => {
+      nullthrows('');
+    }).not.toThrow();
+
+    expect(() => {
+      nullthrows(NaN);
+    }).not.toThrow();
+
+    expect(() => {
+      nullthrows(false);
+    }).not.toThrow();
+  });
+
+  test('it throws', () => {
+    expect(() => {
+      nullthrows(null);
+    }).toThrow(new Error('Got unexpected null'));
 
-  expect(() => {
-    nullthrows(undefined);
-  }).toThrow(new Error('Got unexpected undefined'));
+    expect(() => {
+      nullthrows(undefined);
+    }).toThrow(new Error('Got unexpected undefined'));
 
-  expect(() => {
-    nullthrows(undefined, 'My error message');
-  }).toThrow(new Error('My error message'));
+    expect(() => {
+      nullthrows(undefined, 'My error message');
+    }).toThrow(new Error('My error message'));
+  });
 });

nullthrows.js

@@ -1,12 +1,15 @@
 'use strict';
 
-Object.defineProperty(exports, '__esModule', {value: true});
-
-exports.default = function nullthrows(x, message) {
+function nullthrows(x, message) {
   if (x != null) {
     return x;
   }
   var error = new Error(message !== undefined ? message : 'Got unexpected ' + x);
   error.framesToPop = 1; // Skip nullthrows's own stack frame.
   throw error;
-};
+}
+
+module.exports = nullthrows;
+module.exports.default = nullthrows;
+
+Object.defineProperty(module.exports, '__esModule', {value: true});

nullthrows.js.flow

@@ -1,3 +1,3 @@
 /* @flow */
 
-declare export default function nullthrows<T>(x: ?T, message?: string): T;
+declare module.exports: <T>(x: ?T, message?: string) => T;

package.json

@@ -23,6 +23,7 @@
   },
   "dependencies": {},
   "devDependencies": {
+    "@babel/runtime-corejs2": "^7.0.0",
     "flow-bin": "0.80.0",
     "jest": "^23.5.0",
     "typescript": "3.0.3"

yarn.lock

@@ -16,6 +16,13 @@
     esutils "^2.0.2"
     js-tokens "^4.0.0"
 
+"@babel/runtime-corejs2@^7.0.0":
+  version "7.0.0"
+  resolved "https://registry.yarnpkg.com/@babel/runtime-corejs2/-/runtime-corejs2-7.0.0.tgz#786711ee099c2c2af7875638866c1259eff30a8c"
+  dependencies:
+    core-js "^2.5.7"
+    regenerator-runtime "^0.12.0"
+
 abab@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/abab/-/abab-2.0.0.tgz#aba0ab4c5eee2d4c79d3487d85450fb2376ebb0f"
@@ -526,7 +533,7 @@ copy-descriptor@^0.1.0:
   version "0.1.1"
   resolved "https://registry.yarnpkg.com/copy-descriptor/-/copy-descriptor-0.1.1.tgz#676f6eb3c39997c2ee1ac3a924fd6124748f578d"
 
-core-js@^2.4.0, core-js@^2.5.0:
+core-js@^2.4.0, core-js@^2.5.0, core-js@^2.5.7:
   version "2.5.7"
   resolved "https://registry.yarnpkg.com/core-js/-/core-js-2.5.7.tgz#f972608ff0cead68b841a16a932d0b183791814e"
 
@@ -2415,6 +2422,10 @@ regenerator-runtime@^0.11.0:
   version "0.11.1"
   resolved "https://registry.yarnpkg.com/regenerator-runtime/-/regenerator-runtime-0.11.1.tgz#be05ad7f9bf7d22e056f9726cee5017fbf19e2e9"
 
+regenerator-runtime@^0.12.0:
+  version "0.12.1"
+  resolved "https://registry.yarnpkg.com/regenerator-runtime/-/regenerator-runtime-0.12.1.tgz#fa1a71544764c036f8c49b13a08b2594c9f8a0de"
+
 regex-cache@^0.4.2:
   version "0.4.4"
   resolved "https://registry.yarnpkg.com/regex-cache/-/regex-cache-0.4.4.tgz#75bdc58a2a1496cec48a12835bc54c8d562336dd"