test: add testing framework

index.d.ts

@@ -4,13 +4,3 @@
  */
 
 export * from "./dist";
-
-import { HTMLElement } from "./dist";
-import { IntrinsicElements as JsxIntrinsics } from "./dist/jsx";
-
-declare global {
-    namespace JSX {
-        type Element = HTMLElement;
-        type IntrinsicElements = JsxIntrinsics;
-    }
-}

package.json

@@ -24,7 +24,8 @@
     "scripts": {
         "build": "tsc",
         "clean": "ts-node scripts/clean.ts",
-        "prepublishOnly": "npm run clean && npm run build"
+        "prepublishOnly": "npm run clean && npm run build",
+        "test": "ts-node --project=test/tsconfig.json test/run-tests.ts"
     },
     "devDependencies": {
         "@types/node": "~12",

src/index.ts

@@ -6,3 +6,13 @@
 export { HTMLElement, Component } from "./component";
 export { UserConfig as Config } from "./config";
 export { createElement } from "./create-element";
+
+import { HTMLElement } from "./component";
+import { IntrinsicElements as JsxIntrinsics } from "./jsx";
+
+declare global {
+    namespace JSX {
+        type Element = HTMLElement;
+        type IntrinsicElements = JsxIntrinsics;
+    }
+}

test/lib/expect.ts

@@ -0,0 +1,212 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+import { areEqual, displayValue, matches } from "./utils";
+
+class ExpectError extends Error {
+    public constructor(reason: string, expected: any, actual: any) {
+        super(
+            `${reason}\n` +
+                `\texpected: ${displayValue(expected)}\n` +
+                `\tactual  : ${displayValue(actual)}`
+        );
+    }
+}
+
+/**
+ * A generic expectation builder which knows nothing about the type of value it
+ * is operating upon.
+ *
+ * This is the base class expectation that allows only type-agnostic assertions
+ * upon its contained value, and all other expectation classes inherit from
+ * Expect.
+ */
+export class Expect<T> {
+    protected readonly value: T;
+
+    /**
+     * Create a new expectation around a value.
+     *
+     * @param value Value to place assertions upon.
+     */
+    public constructor(value: T) {
+        this.value = value;
+    }
+
+    /**
+     * Expect the value to equal an expected value.
+     *
+     * Note that strict equality checking is used for primitives and structural
+     * equality is used for objects.
+     *
+     * @param expected Expected value.
+     *
+     * @throws ExpectError If the actual value does not equal the expected value.
+     */
+    public toEqual(expected: T) {
+        if (!areEqual(this.value, expected)) {
+            throw new ExpectError(
+                `value does not equal expected`,
+                expected,
+                this.value
+            );
+        }
+    }
+}
+
+/**
+ * String-specific Expect assertions.
+ */
+export class StringExpect extends Expect<string> {
+    /**
+     * Expect the string value to match a RegExp pattern.
+     *
+     * @param pattern Regular expression to match against.
+     *
+     * @throws ExpectError If the actual value does not match the expected
+     *         RegExp pattern.
+     */
+    public toMatch(pattern: RegExp): void {
+        if (!this.value.match(pattern)) {
+            throw new ExpectError(
+                `value does not match expected pattern`,
+                pattern,
+                this.value
+            );
+        }
+    }
+
+    /**
+     * Expect the string value to start with a particular prefix.
+     *
+     * @param prefix Prefix that the string is expected to start with.
+     *
+     * @throws ExpectError If the actual value does not start with the expected
+     *         prefix.
+     */
+    public toStartWith(prefix: string): void {
+        if (!this.value.startsWith(prefix)) {
+            throw new ExpectError(
+                `value does not start with expected prefix`,
+                prefix,
+                this.value
+            );
+        }
+    }
+
+    /**
+     * Expect the string value to end with a particular suffix.
+     *
+     * @param suffix Suffix that the string is expected to end with.
+     *
+     * @throws ExpectError If the actual value does not end with the expected
+     *         suffix.
+     */
+    public toEndWith(suffix: string): void {
+        if (!this.value.endsWith(suffix)) {
+            throw new ExpectError(
+                `value does not end with expected suffix`,
+                suffix,
+                this.value
+            );
+        }
+    }
+}
+
+/**
+ * Function-specific Expect assertions.
+ */
+export class FunctionExpect<T> extends Expect<() => T> {
+    /**
+     * Expect the function to throw an Error with error message matching a
+     * string or pattern.
+     *
+     * @param pattern String that exactly matches the error message or RegExp
+     *        that should match the error message.
+     *
+     * @throws ExpectError If the function does not throw an error, throws a
+     *         non-Error value, or throws an Error whose message does not match
+     *         the expected pattern.
+     */
+    public toThrowErrorMatching(pattern: string | RegExp): void {
+        try {
+            this.value();
+        } catch (error) {
+            if (!(error instanceof Error)) {
+                throw new ExpectError(
+                    `function threw non-Error value`,
+                    pattern,
+                    error
+                );
+            }
+            if (!matches(error.message, pattern)) {
+                throw new ExpectError(
+                    `thrown Error's message does not match pattern`,
+                    pattern,
+                    error.message
+                );
+            }
+            return;
+        }
+        throw new ExpectError(
+            `function did not throw expected error`,
+            pattern,
+            null
+        );
+    }
+}
+
+/**
+ * Create an Expect assertion builder on a string value.
+ *
+ * @param str String value to place expectations upon.
+ */
+export function expect(str: string): StringExpect;
+/**
+ * Create an Expect assertion builder on a function value.
+ *
+ * Useful primarily for asserting that a function throws an expected Error,
+ * e.g.:
+ *
+ * ```ts
+ * // Passes assertion.
+ * expect(() => throw new Error('oh noes!')).toThrowErrorMatching('oh noes!');
+ *
+ * // Fails assertion since non-error value was thrown in func.
+ * expect(() => throw "oh noes!").toThrow('oh noes!');
+ *
+ * // Fails assertion since func doesn't throw.
+ * expect(() => 1 / 2).toThrowErrorMatching('oh noes!');
+ * ```
+ *
+ * @param fn Function to place expectations upon.
+ */
+export function expect<T>(fn: () => T): FunctionExpect<T>;
+/**
+ * Create an Expect assertion upon some value.
+ *
+ * Expectations are declarative assertions on values that immediately throw an
+ * Error when the assertion is violated. This abstraction allows for readable
+ * test assertions like the following:
+ *
+ * ```ts
+ * // Doesn't throw since strings are equal.
+ * expect("hai").toEqual("hai");
+ *
+ * // Throws an Error since 3 !== 2.
+ * expect(3).toEqual(2);
+ * ```
+ *
+ * @param value Value to place expectations upon.
+ */
+export function expect(value: any): Expect<any> {
+    if (typeof value === "string") {
+        return new StringExpect(value);
+    }
+    if (typeof value === "function") {
+        return new FunctionExpect(value);
+    }
+    return new Expect(value);
+}

test/lib/harness.ts

@@ -0,0 +1,120 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+import { expect } from "./expect";
+import { displayValue, shuffle } from "./utils";
+
+interface Test {
+    readonly name: string;
+
+    runTest(): void | Promise<void>;
+}
+
+type TestResult = {
+    testName: string;
+} & (
+    | {
+          result: "pass";
+      }
+    | {
+          result: "fail";
+          error: Error;
+      }
+);
+
+const runTest = async (test: Test): Promise<TestResult> => {
+    let result: TestResult;
+    try {
+        await test.runTest();
+        result = {
+            testName: test.name,
+            result: "pass",
+        };
+    } catch (error) {
+        result = {
+            testName: test.name,
+            result: "fail",
+            error:
+                error instanceof Error
+                    ? error
+                    : new Error(
+                          `threw non-error object: ${displayValue(error)}`
+                      ),
+        };
+    }
+    return result;
+};
+
+/**
+ * Context object that is passed into a test suite definition.
+ */
+export interface TestSuiteContext {
+    /**
+     * Define a test in this test suite.
+     *
+     * Tests are functions that pass if they are executed and don't throw (or
+     * that resolve for async tests), and that fail if they throw an error (or
+     * reject for async tests).
+     *
+     * Note that tests are executed in a random order within a test suite in
+     * order to prevent accidentally creating order dependencies between tests,
+     * which can result in brittle tests and is a code smell that might indicate
+     * that the code under test is also brittle.
+     */
+    test: (name: string, def: () => void | Promise<void>) => void;
+    /**
+     * Expectation builder function used to build human-readable assertions and
+     * errors.
+     */
+    expect: typeof expect;
+}
+
+/**
+ * Define a suite of tests to run as a single unit.
+ *
+ * A test suite executes immediately, running tests in a randomly determined
+ * order.
+ *
+ * Note that currently there is no support for having multiple test suites per
+ * test file; you CAN have multiple test suites in a file but if the first test
+ * suite fails any subsequent test suites won't be executed.
+ *
+ * @param suiteName Name of the test suite for reporting.
+ * @param def Function used to declare the tests
+ */
+export const testSuite = (
+    suiteName: string,
+    def: (ctx: TestSuiteContext) => void
+): void => {
+    const tests: Test[] = [];
+    const test = (name: string, runTest: () => void | Promise<void>): void => {
+        tests.push({ name, runTest });
+    };
+    def({ test, expect });
+
+    // Randomly shuffle the tests so that we can catch accidental order
+    // dependencies.
+    shuffle(tests);
+    (async () => {
+        const results = await Promise.all(tests.map((test) => runTest(test)));
+        let passed = 0;
+        for (const testResult of results) {
+            if (testResult.result === "fail") {
+                console.error(
+                    `[TEST FAILURE] "${suiteName}": "${testResult.testName}": ` +
+                        `${testResult.error.message}\n`
+                );
+                continue;
+            }
+            passed += 1;
+        }
+        console.info(
+            `[TEST] suite "${suiteName}": ${passed} of ${tests.length} succeeded\n\n`
+        );
+        if (passed < tests.length) {
+            process.exit(1);
+        }
+    })();
+};

test/lib/index.ts

@@ -0,0 +1,6 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+export { testSuite } from "./harness";

test/lib/utils.ts

@@ -0,0 +1,106 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+/**
+ * Randomly rearrange the items of an array in-place.
+ *
+ * @param arr Array to shuffle.
+ */
+export const shuffle = <T>(arr: T[]): void => {
+    let j: number;
+    let x: T;
+    for (let i = arr.length - 1; i > 0; i--) {
+        j = Math.floor(Math.random() * (i + 1));
+        x = arr[i];
+        arr[i] = arr[j];
+        arr[j] = x;
+    }
+};
+
+const areArraysEqual = <T>(a: T[], b: T[]): boolean => {
+    if (a.length != b.length) {
+        return false;
+    }
+    for (let i = 0; i < a.length; i++) {
+        if (!areEqual(a[i], b[i])) {
+            return false;
+        }
+    }
+    return true;
+};
+
+const areObjectsEqual = <T extends object>(a: T, b: T): boolean => {
+    const aKeys = Object.keys(a) as Array<keyof T>;
+    const bKeys = Object.keys(b) as Array<keyof T>;
+    if (aKeys.length !== bKeys.length) {
+        return false;
+    }
+    for (const key of aKeys) {
+        if (!areEqual(a[key], b[key])) {
+            return false;
+        }
+    }
+    return true;
+};
+
+/**
+ * Return whether two values are structurally equal, with support for
+ * primitive values, arrays, deeply nested objects, and RegExp.
+ *
+ * @param a First value to test equality with.
+ * @param b Second value to test equality with.
+ *
+ * @return Whether the two values are structurally equal.
+ */
+export const areEqual = <T>(a: T, b: T): boolean => {
+    if (Array.isArray(a) && Array.isArray(b)) {
+        return areArraysEqual(a, b);
+    }
+    if (a instanceof RegExp && b instanceof RegExp) {
+        return a.source === b.source;
+    }
+    if (typeof a === "object" && typeof b === "object") {
+        return areObjectsEqual(a as any, b);
+    }
+    return a === b;
+};
+
+/**
+ * Return whether a string exactly matches an expected string OR matches a
+ * RegExp pattern.
+ *
+ * If the passed pattern is a string this uses strict equality checking, and
+ * if the passed pattern is a RegExp object it tests the value against it.
+ *
+ * @param value String value to test.
+ * @param pattern String or RegExp pattern to match value against.
+ */
+export const matches = (value: string, pattern: string | RegExp): boolean => {
+    if (typeof pattern === "string") {
+        return value === pattern;
+    }
+    return pattern.test(value);
+};
+
+/**
+ * Render a JavaScript value for debugging and error messages.
+ *
+ * This is essentially JSON.stringify, but with special cases for undefined (
+ * which normally isn't rendered with JSON.stringify) and RegExp (to display
+ * source for the regexp).
+ *
+ * @param value Value to render.
+ *
+ * @return Rendered value to display.
+ */
+export const displayValue = (value: any): string => {
+    if (value === undefined) {
+        return "undefined";
+    }
+    if (value instanceof RegExp) {
+        return value.toString();
+    }
+    return JSON.stringify(value);
+};

test/run-tests.ts

@@ -0,0 +1,20 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+import { fork } from "child_process";
+import * as fs from "fs";
+import * as path from "path";
+
+import { shuffle } from "./lib/utils";
+
+const TEST_SUITES_DIR = path.join(__dirname, "test-suites");
+
+const files = fs.readdirSync(TEST_SUITES_DIR);
+// Shuffle test suites to detect ordering dependencies between them.
+shuffle(files);
+for (const file of files) {
+    const fullPath = path.join(TEST_SUITES_DIR, file);
+    fork(path.relative(process.cwd(), fullPath));
+}

test/test-suites/rendering.tsx

@@ -0,0 +1,64 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+import { createElement } from "../../dist";
+import { renderPage } from "../../dist/render";
+import { testSuite } from "../lib";
+
+testSuite("renderPage", ({ test, expect }) => {
+    test("throws an Error when root elem is not html tag", () => {
+        expect(() => renderPage(<div />)).toThrowErrorMatching(
+            "attempted to render page with non-HTML root element div"
+        );
+    });
+
+    test("outputs a HTML5 DOCTYPE declaration", () => {
+        const html = renderPage(<html />);
+        expect(html).toStartWith("<!DOCTYPE html>");
+    });
+
+    test("escapes HTML in tag names", () => {
+        const html = renderPage(
+            <html>{createElement("div></div", null)}</html>
+        );
+        expect(html).toEqual(
+            "<!DOCTYPE html><html><div&gt;&lt;/div></div&gt;&lt;/div></html>"
+        );
+    });
+
+    test("renders html attributes", () => {
+        const html = renderPage(
+            <html>
+                <div className="test" id="1" />
+            </html>
+        );
+        expect(html).toEqual(
+            '<!DOCTYPE html><html><div class="test" id="1"></div></html>'
+        );
+    });
+
+    test("renders common html tags", () => {
+        const html = renderPage(
+            <html>
+                <head>
+                    <title />
+                </head>
+                <body>
+                    <div />
+                </body>
+            </html>
+        );
+        expect(html).toEqual(
+            "<!DOCTYPE html><html><head><title></title></head><body><div></div></body></html>"
+        );
+    });
+
+    test("renders text nodes", () => {
+        const html = renderPage(<html>There are three lights!</html>);
+        expect(html).toEqual(
+            "<!DOCTYPE html><html>There are three lights!</html>"
+        );
+    });
+});

test/tsconfig.json

@@ -0,0 +1,7 @@
+{
+    "extends": "../tsconfig-base.json",
+    "compilerOptions": {
+        "jsx": "react",
+        "jsxFactory": "createElement"
+    }
+}

tsconfig-base.json

@@ -0,0 +1,14 @@
+{
+    "compilerOptions": {
+        "esModuleInterop": true,
+        "module": "CommonJS",
+        "moduleResolution": "node",
+        "target": "ES2019",
+        "lib": ["ES2019"],
+        "strict": true,
+        "noUnusedLocals": true,
+        "noUnusedParameters": true,
+        "noImplicitReturns": true,
+        "noFallthroughCasesInSwitch": true
+    }
+}

tsconfig.json

@@ -1,18 +1,7 @@
 {
+    "extends": "./tsconfig-base.json",
     "compilerOptions": {
-        "sourceMap": true,
-        "declaration": true,
-        "esModuleInterop": true,
-        "module": "CommonJS",
-        "moduleResolution": "node",
-        "target": "ES2019",
-        "lib": ["ES2019"],
-        "outDir": "./dist",
-        "strict": true,
-        "noUnusedLocals": true,
-        "noUnusedParameters": true,
-        "noImplicitReturns": true,
-        "noFallthroughCasesInSwitch": true
+        "outDir": "./dist"
     },
     "include": ["src/**/*.ts"]
 }