Expose snapshot directory through test.meta

Fixes #1984.

Co-authored-by: Mark Wubben <mark@novemberborn.net>

docs/01-writing-tests.md

@@ -267,14 +267,19 @@ test('context is unicorn', t => {
 });
 ```
 
-## Retrieving test meta data
+## Retrieving test metadata
 
-Helper files can determine the filename of the test being run by reading `test.meta.file`.  This eliminates the need to pass `__filename` from the test to helpers.
+Access data about the currently loaded test file run by reading `test.meta`.
+
+Available properties:
+
+* `file`: path to the test file
+* `snapshotDirectory`: directory where snapshots are stored
 
 ```js
 const test = require('ava');
 
-console.log('Test currently being run: ', test.meta.file);
+console.log('Test file currently being run:', test.meta.file);
 ```
 
 ## Reusing test logic through macros

index.d.ts

@@ -760,6 +760,9 @@ export interface TodoDeclaration {
 export interface MetaInterface {
 	/** Path to the test file being executed. */
 	file: string;
+
+	/** Directory where snapshots are stored. */
+	snapshotDirectory: string;
 }
 
 /** Call to declare a test, or chain to declare hooks or test modifiers */

lib/runner.js

@@ -54,7 +54,11 @@ class Runner extends Emittery {
 		let hasStarted = false;
 		let scheduledStart = false;
 		const meta = Object.freeze({
-			file: options.file
+			file: options.file,
+			get snapshotDirectory() {
+				const {file, snapshotDir: fixedLocation, projectDir} = options;
+				return snapshotManager.determineSnapshotDir({file, fixedLocation, projectDir});
+			}
 		});
 		this.chain = createChain((metadata, testArgs) => { // eslint-disable-line complexity
 			if (hasStarted) {

lib/snapshot-manager.js

@@ -11,6 +11,7 @@ const md5Hex = require('md5-hex');
 const convertSourceMap = require('convert-source-map');
 const slash = require('slash');
 const writeFileAtomic = require('write-file-atomic');
+const mem = require('mem');
 
 const concordanceOptions = require('./concordance-options').snapshotManager;
 
@@ -388,8 +389,26 @@ class Manager {
 	}
 }
 
-function determineSnapshotDir({file, fixedLocation, projectDir}) {
+const resolveSourceFile = mem(file => {
 	const testDir = path.dirname(file);
+	const buffer = tryRead(file);
+	if (!buffer) {
+		return file; // Assume the file is stubbed in our test suite.
+	}
+
+	const source = buffer.toString();
+	const converter = convertSourceMap.fromSource(source) || convertSourceMap.fromMapFileSource(source, testDir);
+	if (converter) {
+		const map = converter.toObject();
+		const firstSource = `${map.sourceRoot || ''}${map.sources[0]}`;
+		return path.resolve(testDir, firstSource);
+	}
+
+	return file;
+});
+
+const determineSnapshotDir = mem(({file, fixedLocation, projectDir}) => {
+	const testDir = path.dirname(resolveSourceFile(file));
 	if (fixedLocation) {
 		const relativeTestLocation = path.relative(projectDir, testDir);
 		return path.join(fixedLocation, relativeTestLocation);
@@ -405,30 +424,13 @@ function determineSnapshotDir({file, fixedLocation, projectDir}) {
 	}
 
 	return testDir;
-}
+}, {cacheKey: ([{file}]) => file});
 
-function resolveSourceFile(file) {
-	const testDir = path.dirname(file);
-	const buffer = tryRead(file);
-	if (!buffer) {
-		return file; // Assume the file is stubbed in our test suite.
-	}
-
-	const source = buffer.toString();
-	const converter = convertSourceMap.fromSource(source) || convertSourceMap.fromMapFileSource(source, testDir);
-	if (converter) {
-		const map = converter.toObject();
-		const firstSource = `${map.sourceRoot || ''}${map.sources[0]}`;
-		return path.resolve(testDir, firstSource);
-	}
-
-	return file;
-}
+exports.determineSnapshotDir = determineSnapshotDir;
 
 function load({file, fixedLocation, projectDir, recordNewSnapshots, updating}) {
-	const sourceFile = resolveSourceFile(file);
-	const dir = determineSnapshotDir({file: sourceFile, fixedLocation, projectDir});
-	const relFile = path.relative(projectDir, sourceFile);
+	const dir = determineSnapshotDir({file, fixedLocation, projectDir});
+	const relFile = path.relative(projectDir, resolveSourceFile(file));
 	const name = path.basename(relFile);
 	const reportFile = `${name}.md`;
 	const snapFile = `${name}.snap`;

package.json

@@ -116,6 +116,7 @@
 		"esm": "^3.2.25",
 		"execa": "^4.0.0",
 		"get-stream": "^5.1.0",
+		"mem": "^6.0.1",
 		"nyc": "^15.0.1",
 		"p-event": "^4.1.0",
 		"proxyquire": "^2.1.3",

test-tap/api.js

@@ -30,12 +30,12 @@ function apiCreator(options = {}) {
 	return instance;
 }
 
-test('test.meta.file', t => {
-	const api = apiCreator();
+test('test.meta', t => {
+	const api = apiCreator({snapshotDir: 'snapshot-fixture'});
 
-	return api.run({files: [path.join(__dirname, 'fixture/meta.js')]})
+	return api.run({files: [path.join(__dirname, 'fixture', 'meta.js')]})
 		.then(runStatus => {
-			t.is(runStatus.stats.passedTests, 2);
+			t.is(runStatus.stats.passedTests, 3);
 		});
 });
 

test-tap/fixture/meta.js

@@ -1,9 +1,14 @@
 const {default: test, meta} = require('../..');
 
+test('meta is test.meta', t => {
+	t.is(meta, test.meta);
+});
+
 test('meta.file', t => {
 	t.is(meta.file, __filename);
 });
 
-test('test.meta.file', t => {
-	t.is(test.meta.file, __filename);
+test('meta.snapshotDirectory', t => {
+	t.regex(meta.snapshotDirectory, /snapshot-fixture/);
 });
+