src/vs/base/test/common/snapshot.ts
187 LOC · 180 covered · 7 uncovered · 45 ranges · 686 concepts · 13 introducers · 306 tests
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/*---------------------------------------------------------------------------------------------
snapshot.ts ×5
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* Copyright (c) Microsoft Corporation. All rights reserved.
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* Licensed under the MIT License. See License.txt in the project root for license information.
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*--------------------------------------------------------------------------------------------*/
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import { Lazy } from '../../common/lazy.js';
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import { FileAccess } from '../../common/network.js';
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import { URI } from '../../common/uri.js';
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declare const __readFileInTests: (path: string) => Promise<string>;
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declare const __writeFileInTests: (path: string, contents: string) => Promise<void>;
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declare const __readDirInTests: (path: string) => Promise<string[]>;
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declare const __unlinkInTests: (path: string) => Promise<void>;
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declare const __mkdirPInTests: (path: string) => Promise<void>;
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// setup on import so assertSnapshot has the current context without explicit passing
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let context: Lazy<SnapshotContext> | undefined;
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const sanitizeName = (name: string) => name.replace(/[^a-z0-9_-]/gi, '_');
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const normalizeCrlf = (str: string) => str.replace(/\r\n/g, '\n');
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export interface ISnapshotOptions {
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/** Name for snapshot file, rather than an incremented number */
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name?: string;
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/** Extension name of the snapshot file, defaults to `.snap` */
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extension?: string;
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}
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/**
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* This is exported only for tests against the snapshotting itself! Use
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* {@link assertSnapshot} as a consumer!
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*/
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export class SnapshotContext {
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private nextIndex = 0;
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protected snapshotsDir: URI;
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private readonly namePrefix: string;
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private readonly usedNames = new Set();
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constructor(private readonly test: Mocha.Test | undefined) {
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throw new Error('assertSnapshot can only be used in a test');
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}
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if (!test.file) {
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throw new Error('currentTest.file is not set, please open an issue with the test you\'re trying to run');
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}
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const src = URI.joinPath(FileAccess.asFileUri(''), '../src');
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const parts = test.file.split(/[/\\]/g);
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this.namePrefix = sanitizeName(test.fullTitle()) + '.';
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this.snapshotsDir = URI.joinPath(src, ...[...parts.slice(0, -1), '__snapshots__']);
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}
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public async assert(value: unknown, options?: ISnapshotOptions) {
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const originalStack = new Error().stack!; // save to make the stack nicer on failure
snapshot.ts ×12
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const nameOrIndex = (options?.name ? sanitizeName(options.name) : this.nextIndex++);
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const fileName = this.namePrefix + nameOrIndex + '.' + (options?.extension || 'snap');
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this.usedNames.add(fileName);
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const fpath = URI.joinPath(this.snapshotsDir, fileName).fsPath;
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const actual = formatValue(value);
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let expected: string;
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try {
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expected = await __readFileInTests(fpath);
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} catch {
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await __mkdirPInTests(this.snapshotsDir.fsPath);
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await __writeFileInTests(fpath, actual);
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return;
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}
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if (normalizeCrlf(expected) !== normalizeCrlf(actual)) {
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const err: any = new Error(`Snapshot #${nameOrIndex} does not match expected output`);
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err.expected = expected;
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err.actual = actual;
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err.snapshotPath = fpath;
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err.stack = (err.stack as string)
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.split('\n')
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// remove all frames from the async stack and keep the original caller's frame
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.slice(0, 1)
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.concat(originalStack.split('\n').slice(3))
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.join('\n');
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throw err;
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}
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public async removeOldSnapshots() {
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const toDelete = contents.filter(f => f.startsWith(this.namePrefix) && !this.usedNames.has(f));
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if (toDelete.length) {
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console.info(`Deleting ${toDelete.length} old snapshots for ${this.test?.fullTitle()}`);
snapshot.ts ×1
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}
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await Promise.all(toDelete.map(f => __unlinkInTests(URI.joinPath(this.snapshotsDir, f).fsPath)));
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}
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const debugDescriptionSymbol = Symbol.for('debug.description');
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function formatValue(value: unknown, level = 0, seen: unknown[] = []): string {
snapshot.ts ×12
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switch (typeof value) {
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case 'bigint':
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case 'boolean':
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case 'number':
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case 'symbol':
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case 'undefined':
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}
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}
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}
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if (debugDescriptionSymbol in value && typeof (value as any)[debugDescriptionSymbol] === 'function') {
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return (value as any)[debugDescriptionSymbol]();
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}
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const ci = ' '.repeat(level + 1);
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if (Array.isArray(value)) {
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const multiline = children.some(c => c.includes('\n')) || children.join(', ').length > 80;
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return multiline ? `[\n${ci}${children.join(`,\n${ci}`)}\n${oi}]` : `[ ${children.join(', ')} ]`;
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}
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let entries;
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let prefix = '';
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if (value instanceof Map) {
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entries = [...value.entries()];
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entries = [...value.entries()];
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entries = Object.entries(value);
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}
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const lines = entries.map(([k, v]) => `${k}: ${formatValue(v, level + 1, [...seen, value])}`);
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return prefix + (lines.length > 1
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throw new Error(`Unknown type ${value}`);
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}
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setup(function () {
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const currentTest = this.currentTest;
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context = new Lazy(() => new SnapshotContext(currentTest));
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});
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teardown(async function () {
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if (this.currentTest?.state === 'passed') {
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await context?.rawValue?.removeOldSnapshots();
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}
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context = undefined;
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});
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/**
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* Implements a snapshot testing utility. ⚠️ This is async! ⚠️
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*
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* The first time a snapshot test is run, it'll record the value it's called
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* with as the expected value. Subsequent runs will fail if the value differs,
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* but the snapshot can be regenerated by hand or using the Selfhost Test
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* Provider Extension which'll offer to update it.
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*
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* The snapshot will be associated with the currently running test and stored
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* in a `__snapshots__` directory next to the test file, which is expected to
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* be the first `.test.js` file in the callstack.
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*/
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export function assertSnapshot(value: unknown, options?: ISnapshotOptions): Promise<void> {
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throw new Error('assertSnapshot can only be used in a test');
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}
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return context.value.assert(value, options);
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}