From 85af7dd4cb5e81a40d2c574a3ccfe8f6a8113ee0 Mon Sep 17 00:00:00 2001
From: Marc Cataford <mcat@riseup.net>
Date: Sat, 15 Apr 2023 22:50:21 -0400
Subject: [PATCH] feat: basic beforeEach, afterEach support (#28)

---
 src/index.ts                |  1 +
 src/testComponents/hooks.ts |  9 +++++++++
 src/testContext.ts          | 29 +++++++++++++++++++++++++++++
 tests/hooks.test.ts         | 32 ++++++++++++++++++++++++++++++++
 4 files changed, 71 insertions(+)
 create mode 100644 src/testComponents/hooks.ts
 create mode 100644 tests/hooks.test.ts

diff --git a/src/index.ts b/src/index.ts
index c8ba9c2..908e7dd 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,3 +1,4 @@
 export { default as test, it } from './testComponents/test'
 export { default as describe } from './testComponents/describe'
 export { default as expect } from './testComponents/expect'
+export { beforeEach, afterEach } from './testComponents/hooks'
diff --git a/src/testComponents/hooks.ts b/src/testComponents/hooks.ts
new file mode 100644
index 0000000..7c591a9
--- /dev/null
+++ b/src/testComponents/hooks.ts
@@ -0,0 +1,9 @@
+import { getTestContext } from '../testContext'
+
+export function beforeEach(func: () => void) {
+	getTestContext().addBeforeEach(func)
+}
+
+export function afterEach(func: () => void) {
+	getTestContext().addAfterEach(func)
+}
diff --git a/src/testContext.ts b/src/testContext.ts
index 9df1b9d..7828ebd 100644
--- a/src/testContext.ts
+++ b/src/testContext.ts
@@ -21,6 +21,8 @@ export function setContext(context: TestContext | null) {
 export class TestContext {
 	children: Map<string, TestContext>
 	tests: Map<TestCaseLabel, TestCaseFunction>
+	beforeEach?: () => void
+	afterEach?: () => void
 	parentContext?: TestContext | null
 
 	constructor(parentContext: TestContext | null = null) {
@@ -39,11 +41,38 @@ export class TestContext {
 		return childContext
 	}
 
+	addBeforeEach(func: () => void) {
+		if (this.beforeEach) throw new Error('beforeEach is already defined on context.')
+		this.beforeEach = func
+	}
+
+	addAfterEach(func: () => void) {
+		if (this.afterEach) throw new Error('afterEach is already defined on context.')
+		this.afterEach = func
+	}
+
+	get allBeforeEach(): Array<() => void> {
+		if (!this.beforeEach) return this.parentContext?.allBeforeEach ?? [() => {}]
+
+		const parentBeforeEach = !this.parentContext ? [] : this.parentContext.allBeforeEach
+
+		return [...parentBeforeEach, this.beforeEach]
+	}
+
+	get allAfterEach(): Array<() => void> {
+		if (!this.afterEach) return this.parentContext?.allAfterEach ?? [() => {}]
+
+		const parentAfterEach = !this.parentContext ? [] : this.parentContext.allAfterEach
+
+		return [...parentAfterEach, this.afterEach]
+	}
 	runTest(label: TestCaseLabel, test: TestCaseFunction) {
 		performance.mark(`test-${label}:start`)
 		let hasFailed = false
 		try {
+			this.allBeforeEach.forEach((func) => func())
 			test()
+			this.allAfterEach.forEach((func) => func())
 		} catch (e) {
 			hasFailed = true
 			logger.logError(String(e))
diff --git a/tests/hooks.test.ts b/tests/hooks.test.ts
new file mode 100644
index 0000000..3f0ca0c
--- /dev/null
+++ b/tests/hooks.test.ts
@@ -0,0 +1,32 @@
+import assert from 'assert'
+
+import { test, describe, beforeEach, afterEach, expect } from 'works-on-my-machine'
+
+describe('Test group lifecycle hooks', () => {
+	let outer: boolean = false
+
+	beforeEach(() => {
+		outer = true
+	})
+
+	afterEach(() => {
+		outer = false
+	})
+
+	describe('beforeEach', () => {
+		let inner: boolean = false
+
+		beforeEach(() => {
+			inner = true
+		})
+
+		afterEach(() => {
+			inner = false
+		})
+
+		test('all beforeEach side-effects run before each test runs', () => {
+			expect(inner).toBe(true)
+			expect(outer).toBe(true)
+		})
+	})
+})