test(bezier-react): add test code to assert (channel-io#1770)

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## Related Issue
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<!-- Fixes #0000 -->

## Summary
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add test code to assert

## Details
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<img width="636" alt="image"
src="https://github.com/channel-io/bezier-react/assets/102217654/8672d1ae-d8ce-4b33-997e-149be16963a7">


### Breaking change? (Yes/No)
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## References
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aware of -->

---------

Co-authored-by: Ed <[email protected]>

packages/bezier-react/src/utils/assert.test.ts

@@ -0,0 +1,92 @@
+import {
+  AssertionException,
+  assert,
+  isDev,
+  warn,
+} from './assert'
+
+describe('isDev', () => {
+  const ORIGINAL_ENV = process.env
+
+  beforeEach(() => {
+    jest.resetModules()
+    process.env = { ...ORIGINAL_ENV }
+  })
+
+  afterAll(() => {
+    process.env = ORIGINAL_ENV
+  })
+
+  it('should return true when NODE_ENV is not production', () => {
+    process.env.NODE_ENV = 'development'
+
+    const result = isDev()
+
+    expect(result).toBe(true)
+  })
+
+  it('should return false when NODE_ENV is production', () => {
+    process.env.NODE_ENV = 'production'
+
+    const result = isDev()
+
+    expect(result).toBe(false)
+  })
+})
+
+describe('assert', () => {
+  const ORIGINAL_ENV = process.env
+
+  beforeEach(() => {
+    jest.resetModules()
+    process.env = { ...ORIGINAL_ENV }
+  })
+
+  afterAll(() => {
+    process.env = ORIGINAL_ENV
+  })
+
+  it('should throw an assertion exception error in development environment when the predicate is false', () => {
+    process.env.NODE_ENV = 'development'
+
+    expect(() => assert(false)).toThrow(new AssertionException())
+  })
+
+  it('should throw an "failed" with a error in development environment when the predicate is false', () => {
+    process.env.NODE_ENV = 'development'
+
+    expect(() => assert(false, 'failed')).toThrow(new AssertionException('failed'))
+  })
+
+  it('should not throw in production environment when the predicate is true', () => {
+    process.env.NODE_ENV = 'production'
+
+    expect(() => assert(true)).not.toThrow(new AssertionException())
+  })
+})
+
+describe('warn', () => {
+  const ORIGINAL_ENV = process.env
+
+  beforeEach(() => {
+    jest.resetModules()
+    process.env = { ...ORIGINAL_ENV }
+  })
+
+  afterAll(() => {
+    process.env = ORIGINAL_ENV
+  })
+
+  it('should output the message using console.warn if the message argument is passed', () => {
+    process.env.NODE_ENV = 'development'
+
+    const warnSpy = jest.spyOn(console, 'warn')
+
+    warn('Warn')
+
+    expect(warnSpy).toHaveBeenCalled()
+    expect(warnSpy).toHaveBeenCalledWith('Warn')
+
+    warnSpy.mockRestore()
+  })
+})

packages/bezier-react/src/utils/assert.ts

@@ -1,4 +1,4 @@
-function isDev() {
+export function isDev() {
   return process.env.NODE_ENV !== 'production'
 }
 
@@ -9,7 +9,7 @@ export function warn(message: string) {
   }
 }
 
-class AssertionException extends Error {
+export class AssertionException extends Error {
   constructor(message?: string) {
     super()