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This commit adds a t.assert.snapshot() method that implements snapshot testing.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,234 @@ | ||
| 'use strict'; | ||
| const { | ||
| ArrayPrototypeJoin, | ||
| ArrayPrototypeMap, | ||
| ArrayPrototypeSort, | ||
| JSONStringify, | ||
| ObjectKeys, | ||
| SafeMap, | ||
| String, | ||
| StringPrototypeReplaceAll, | ||
| } = primordials; | ||
| const { | ||
| codes: { | ||
| ERR_INVALID_STATE, | ||
| }, | ||
| } = require('internal/errors'); | ||
| const { emitExperimentalWarning, kEmptyObject } = require('internal/util'); | ||
| let debug = require('internal/util/debuglog').debuglog('test_runner', (fn) => { | ||
| debug = fn; | ||
| }); | ||
| const { | ||
| validateArray, | ||
| validateFunction, | ||
| validateObject, | ||
| } = require('internal/validators'); | ||
| const { strictEqual } = require('assert'); | ||
| const { mkdirSync, readFileSync, writeFileSync } = require('fs'); | ||
| const { dirname } = require('path'); | ||
| const { createContext, runInContext } = require('vm'); | ||
| const kExperimentalWarning = 'Snapshot testing'; | ||
| const kMissingSnapshotTip = 'Missing snapshots can be generated by rerunning ' + | ||
| 'the command with the --test-update-snapshots flag.'; | ||
| const defaultSerializers = [ | ||
| (value) => { return JSONStringify(value, null, 2); }, | ||
| ]; | ||
|
|
||
| function defaultResolveSnapshotPath(testPath) { | ||
| if (typeof testPath !== 'string') { | ||
| return testPath; | ||
| } | ||
|
|
||
| return `${testPath}.snapshot`; | ||
| } | ||
|
|
||
| let resolveSnapshotPathFn = defaultResolveSnapshotPath; | ||
| let serializerFns = defaultSerializers; | ||
|
|
||
| function setResolveSnapshotPath(fn) { | ||
| emitExperimentalWarning(kExperimentalWarning); | ||
| validateFunction(fn, 'fn'); | ||
| resolveSnapshotPathFn = fn; | ||
| } | ||
|
|
||
| function setDefaultSerializers(serializers) { | ||
| emitExperimentalWarning(kExperimentalWarning); | ||
| validateFunctionArray(serializers, 'serializers'); | ||
| serializerFns = ArrayPrototypeMap(serializers, (fn) => { | ||
| return fn; | ||
| }); | ||
| } | ||
|
|
||
| class SnapshotManager { | ||
| constructor(entryFile, updateSnapshots) { | ||
| this.entryFile = entryFile; | ||
| this.snapshotFile = undefined; | ||
| this.snapshots = { __proto__: null }; | ||
| this.nameCounts = new SafeMap(); | ||
| // A manager instance will only read or write snapshot files based on the | ||
| // updateSnapshots argument. | ||
| this.loaded = updateSnapshots; | ||
| this.updateSnapshots = updateSnapshots; | ||
| } | ||
|
|
||
| resolveSnapshotFile() { | ||
| if (this.snapshotFile === undefined) { | ||
| const resolved = resolveSnapshotPathFn(this.entryFile); | ||
|
|
||
| if (typeof resolved !== 'string') { | ||
| const err = new ERR_INVALID_STATE('Invalid snapshot filename.'); | ||
| err.filename = resolved; | ||
| throw err; | ||
| } | ||
|
|
||
| this.snapshotFile = resolved; | ||
| } | ||
| } | ||
|
|
||
| serialize(input, serializers = serializerFns) { | ||
| try { | ||
| let value = input; | ||
|
|
||
| for (let i = 0; i < serializers.length; ++i) { | ||
| const fn = serializers[i]; | ||
| value = fn(value); | ||
| } | ||
|
|
||
| return `\n${templateEscape(value)}\n`; | ||
| } catch (err) { | ||
| const error = new ERR_INVALID_STATE( | ||
| 'The provided serializers did not generate a string.', | ||
| ); | ||
| error.input = input; | ||
| error.cause = err; | ||
| throw error; | ||
| } | ||
| } | ||
|
|
||
| getSnapshot(id) { | ||
| if (!(id in this.snapshots)) { | ||
| const err = new ERR_INVALID_STATE(`Snapshot '${id}' not found in ` + | ||
| `'${this.snapshotFile}.' ${kMissingSnapshotTip}`); | ||
| err.snapshot = id; | ||
| err.filename = this.snapshotFile; | ||
| throw err; | ||
| } | ||
|
|
||
| return this.snapshots[id]; | ||
| } | ||
|
|
||
| setSnapshot(id, value) { | ||
| this.snapshots[templateEscape(id)] = value; | ||
| } | ||
|
|
||
| nextId(name) { | ||
| const count = this.nameCounts.get(name) ?? 1; | ||
|
|
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| this.nameCounts.set(name, count + 1); | ||
| return `${name} ${count}`; | ||
| } | ||
|
|
||
| readSnapshotFile() { | ||
| if (this.loaded) { | ||
| debug('skipping read of snapshot file'); | ||
| return; | ||
| } | ||
|
|
||
| try { | ||
| const source = readFileSync(this.snapshotFile, 'utf8'); | ||
| const context = { __proto__: null, exports: { __proto__: null } }; | ||
|
|
||
| createContext(context); | ||
| runInContext(source, context); | ||
|
|
||
| if (context.exports === null || typeof context.exports !== 'object') { | ||
| throw new ERR_INVALID_STATE( | ||
| `Malformed snapshot file '${this.snapshotFile}'.`, | ||
| ); | ||
| } | ||
|
|
||
| this.snapshots = context.exports; | ||
| this.loaded = true; | ||
| } catch (err) { | ||
| let msg = `Cannot read snapshot file '${this.snapshotFile}.'`; | ||
|
|
||
| if (err?.code === 'ENOENT') { | ||
| msg += ` ${kMissingSnapshotTip}`; | ||
| } | ||
|
|
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| const error = new ERR_INVALID_STATE(msg); | ||
| error.cause = err; | ||
| error.filename = this.snapshotFile; | ||
| throw error; | ||
| } | ||
| } | ||
|
|
||
| writeSnapshotFile() { | ||
| if (!this.updateSnapshots) { | ||
| debug('skipping write of snapshot file'); | ||
| return; | ||
| } | ||
|
|
||
| const keys = ArrayPrototypeSort(ObjectKeys(this.snapshots)); | ||
| const snapshotStrings = ArrayPrototypeMap(keys, (key) => { | ||
| return `exports[\`${key}\`] = \`${this.snapshots[key]}\`;\n`; | ||
| }); | ||
| const output = ArrayPrototypeJoin(snapshotStrings, '\n'); | ||
| mkdirSync(dirname(this.snapshotFile), { __proto__: null, recursive: true }); | ||
| writeFileSync(this.snapshotFile, output, 'utf8'); | ||
| } | ||
|
|
||
| createAssert() { | ||
| const manager = this; | ||
|
|
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| return function snapshotAssertion(actual, options = kEmptyObject) { | ||
| emitExperimentalWarning(kExperimentalWarning); | ||
| // Resolve the snapshot file here so that any resolution errors are | ||
| // surfaced as early as possible. | ||
| manager.resolveSnapshotFile(); | ||
|
|
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| const { fullName } = this; | ||
| const id = manager.nextId(fullName); | ||
|
|
||
| validateObject(options, 'options'); | ||
|
|
||
| const { | ||
| serializers = serializerFns, | ||
| } = options; | ||
|
|
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| validateFunctionArray(serializers, 'options.serializers'); | ||
|
|
||
| const value = manager.serialize(actual, serializers); | ||
|
|
||
| if (manager.updateSnapshots) { | ||
| manager.setSnapshot(id, value); | ||
| } else { | ||
| manager.readSnapshotFile(); | ||
| strictEqual(value, manager.getSnapshot(id)); | ||
| } | ||
| }; | ||
| } | ||
| } | ||
|
|
||
| function validateFunctionArray(fns, name) { | ||
| validateArray(fns, name); | ||
| for (let i = 0; i < fns.length; ++i) { | ||
| validateFunction(fns[i], `${name}[${i}]`); | ||
| } | ||
| } | ||
|
|
||
| function templateEscape(str) { | ||
| let result = String(str); | ||
| result = StringPrototypeReplaceAll(result, '\\', '\\\\'); | ||
| result = StringPrototypeReplaceAll(result, '`', '\\`'); | ||
| result = StringPrototypeReplaceAll(result, '${', '\\${'); | ||
| return result; | ||
| } | ||
|
|
||
| module.exports = { | ||
| SnapshotManager, | ||
| defaultResolveSnapshotPath, // Exported for testing only. | ||
| defaultSerializers, // Exported for testing only. | ||
| setDefaultSerializers, | ||
| setResolveSnapshotPath, | ||
| }; |
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1 change: 1 addition & 0 deletions
1
test/fixtures/test-runner/snapshots/malformed-exports.js.snapshot
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1 @@ | ||
| exports = null; |
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