test: ✅ add more tests

README.md

@@ -1,5 +1,7 @@
 # next-runtime-env - Runtime Environment Configuration
 
+[![codecov](https://codecov.io/gh/expatfile/next-runtime-env/branch/main/graph/badge.svg?token=mbGgsweFuP)](https://codecov.io/gh/expatfile/next-runtime-env)
+
 Populates your environment at **run-time** rather than **build-time**.
 
 - Isomorphic - Server, browser and middleware compatible.
@@ -20,7 +22,7 @@ const {
 configureRuntimeEnv();
 ```
 
-This will generates a `__ENV.js` file that contains white-listed environment variables that have a `NEXT_PUBLIC_` prefix.
+This will generates a `__ENV.js` file that contains allow-listed environment variables that have a `NEXT_PUBLIC_` prefix.
 
 2. Add the following to the head section fo your `pages/_document.js`:
 

src/helpers/get-public-env.spec.ts

@@ -0,0 +1,57 @@
+import { getPublicEnv } from './get-public-env';
+
+describe('getPublicEnv', () => {
+  afterEach(() => {
+    delete process.env.FOO;
+    delete process.env.BAR;
+    delete process.env.BAR;
+    delete process.env.NEXT_PUBLIC_FOO;
+    delete process.env.NEXT_PUBLIC_BAR;
+    delete process.env.NEXT_PUBLIC_BAZ;
+  });
+
+  it('should return a allow-listed value', () => {
+    process.env.NEXT_PUBLIC_FOO = 'foo';
+
+    expect(getPublicEnv()).toEqual({
+      NEXT_PUBLIC_FOO: 'foo',
+    });
+  });
+
+  it('should return multiple allow-listed values', () => {
+    process.env.NEXT_PUBLIC_FOO = 'foo';
+    process.env.NEXT_PUBLIC_BAR = 'bar';
+    process.env.NEXT_PUBLIC_BAZ = 'baz';
+
+    expect(getPublicEnv()).toEqual({
+      NEXT_PUBLIC_FOO: 'foo',
+      NEXT_PUBLIC_BAR: 'bar',
+      NEXT_PUBLIC_BAZ: 'baz',
+    });
+  });
+
+  it('should not return a non allow-listed value', () => {
+    process.env.FOO = 'foo';
+
+    expect(getPublicEnv()).toEqual({});
+  });
+
+  it('should not return multiple non allow-listed values', () => {
+    process.env.FOO = 'foo';
+    process.env.BAR = 'bar';
+    process.env.BAZ = 'baz';
+
+    expect(getPublicEnv()).toEqual({});
+  });
+
+  it('should not return a mixed list of allow-listed and non allow-listed values', () => {
+    process.env.NEXT_PUBLIC_FOO = 'foo';
+    process.env.BAR = 'bar';
+    process.env.NEXT_PUBLIC_BAZ = 'baz';
+
+    expect(getPublicEnv()).toEqual({
+      NEXT_PUBLIC_FOO: 'foo',
+      NEXT_PUBLIC_BAZ: 'baz',
+    });
+  });
+});

src/helpers/write-browser-env.spec.ts

@@ -0,0 +1,74 @@
+import fs from 'fs';
+
+import { writeBrowserEnv } from './write-browser-env';
+
+const infoSpy = jest.spyOn(console, 'info');
+
+const base = fs.realpathSync(process.cwd());
+const path = `${base}/public`;
+const file = `${path}/__ENV.js`;
+
+beforeAll(() => {
+  infoSpy.mockImplementation();
+
+  fs.mkdirSync(path);
+});
+
+afterAll(() => {
+  infoSpy.mockRestore();
+
+  fs.rmdirSync(path);
+});
+
+describe('writeBrowserEnv', () => {
+  afterEach(() => {
+    fs.rmSync(file);
+  });
+
+  it('should write an empty env', () => {
+    writeBrowserEnv({});
+
+    expect(infoSpy).toHaveBeenCalledWith(
+      'next-runtime-env: Writing browser runtime env',
+      file
+    );
+
+    const content = fs.readFileSync(file).toString();
+
+    expect(content).toEqual('window.__ENV = {};');
+  });
+
+  it('should write and env with a value', () => {
+    writeBrowserEnv({
+      NEXT_PUBLIC_FOO: 'foo',
+    });
+
+    expect(infoSpy).toHaveBeenCalledWith(
+      'next-runtime-env: Writing browser runtime env',
+      file
+    );
+
+    const content = fs.readFileSync(file).toString();
+
+    expect(content).toEqual('window.__ENV = {"NEXT_PUBLIC_FOO":"foo"};');
+  });
+
+  it('should write and env with multiple values', () => {
+    writeBrowserEnv({
+      NEXT_PUBLIC_FOO: 'foo',
+      NEXT_PUBLIC_BAR: 'bar',
+      NEXT_PUBLIC_BAZ: 'baz',
+    });
+
+    expect(infoSpy).toHaveBeenCalledWith(
+      'next-runtime-env: Writing browser runtime env',
+      file
+    );
+
+    const content = fs.readFileSync(file).toString();
+
+    expect(content).toEqual(
+      'window.__ENV = {"NEXT_PUBLIC_FOO":"foo","NEXT_PUBLIC_BAR":"bar","NEXT_PUBLIC_BAZ":"baz"};'
+    );
+  });
+});

src/helpers/write-browser-env.ts

@@ -11,7 +11,7 @@ export function writeBrowserEnv(env: NodeJS.ProcessEnv) {
   // eslint-disable-next-line no-console
   console.info('next-runtime-env: Writing browser runtime env', path);
 
-  const populate = `window.__ENV = ${JSON.stringify(env)};`;
+  const content = `window.__ENV = ${JSON.stringify(env)};`;
 
-  fs.writeFileSync(path, populate);
+  fs.writeFileSync(path, content);
 }

src/index.ts

@@ -1,3 +1,5 @@
+/* istanbul ignore file */
+
 // This allows TypeScript to detect our global value.
 declare global {
   interface Window {