Added test suite for compiler

src/support/compiler.spec.ts

@@ -0,0 +1,27 @@
+import webpack from 'webpack'
+
+import {
+  getWebpackCompiler,
+  registerWebpackCompiler,
+} from './compiler'
+
+describe('compiler', () => {
+  const compiler = webpack({})
+
+  beforeAll(() => {
+    registerWebpackCompiler(compiler)
+  })
+
+  test('can get registered webpack compiler', () => {
+    expect(getWebpackCompiler()).toMatchObject(compiler)
+  })
+
+  test('can register a new webpack compiler', () => {
+    const newCompiler = webpack({})
+
+    registerWebpackCompiler(newCompiler)
+
+    expect(getWebpackCompiler()).toMatchObject(newCompiler)
+    expect(getWebpackCompiler()).not.toMatchObject(compiler)
+  })
+})