Support deletion in process.env too (#5466)

CHANGELOG.md

@@ -2,12 +2,19 @@
 
 ### Features
 
+* `[jest-util]` Add deletion to `process.env` as well
+  ([#5466](https://github.com/facebook/jest/pull/5466))
+* `[jest-util]` Add case-insensitive getters/setters to `process.env`
+  ([#5465](https://github.com/facebook/jest/pull/5465))
 * `[jest-mock]` Add util methods to create async functions.
   ([#5318](https://github.com/facebook/jest/pull/5318))
 
 ### Fixes
 
-* `[jest-cli]` Hide interactive mode if there are no failed snapshot tests ([#5450](https://github.com/facebook/jest/pull/5450))
+* `[jest-cli]` Add trailing slash when checking root folder
+  ([#5464](https://github.com/facebook/jest/pull/5464))
+* `[jest-cli]` Hide interactive mode if there are no failed snapshot tests
+  ([#5450](https://github.com/facebook/jest/pull/5450))
 * `[babel-jest]` Remove retainLines from babel-jest
   ([#5326](https://github.com/facebook/jest/pull/5439))
 * `[jest-cli]` Glob patterns ignore non-`require`-able files (e.g. `README.md`)

packages/jest-util/src/__tests__/create_process_object.test.js

@@ -54,6 +54,18 @@ it('checks that process.env works as expected on Linux platforms', () => {
 
   expect(fake.PROP_ADDED).toBe('new!');
   expect(process.env.PROP_ADDED).toBe(undefined);
+
+  // You can delete properties, but they are case sensitive!
+  fake.prop = 'foo';
+  fake.PROP = 'bar';
+
+  expect(fake.prop).toBe('foo');
+  expect(fake.PROP).toBe('bar');
+
+  delete fake.PROP;
+
+  expect(fake.prop).toBe('foo');
+  expect(fake.PROP).toBe(undefined);
 });
 
 it('checks that process.env works as expected in Windows platforms', () => {
@@ -73,4 +85,10 @@ it('checks that process.env works as expected in Windows platforms', () => {
 
   expect(typeof fake.tostring).toBe('undefined');
   expect(typeof fake.valueof).toBe('undefined');
+
+  // You can delete through case-insensitiveness too.
+  delete fake.prop_string;
+
+  expect(fake.hasOwnProperty('PROP_STRING')).toBe(false);
+  expect(fake.hasOwnProperty('PROP_string')).toBe(false);
 });

packages/jest-util/src/create_process_object.js

@@ -23,8 +23,28 @@ function createProcessEnv() {
   const lookup = {};
 
   const proxy = new Proxy(real, {
+    deleteProperty(target, key) {
+      for (const name in real) {
+        if (real.hasOwnProperty(name)) {
+          if (typeof key === 'string' && process.platform === 'win32') {
+            if (name.toLowerCase() === key.toLowerCase()) {
+              delete real[name];
+              delete lookup[name.toLowerCase()];
+            }
+          } else {
+            if (key === name) {
+              delete real[name];
+              delete lookup[name];
+            }
+          }
+        }
+      }
+
+      return true;
+    },
+
     get(target, key) {
-      if ((typeof key === 'string') && (process.platform === 'win32')) {
+      if (typeof key === 'string' && process.platform === 'win32') {
         return lookup[key in proto ? key : key.toLowerCase()];
       } else {
         return real[key];