Track snapshot files touched during test run, ignore in watcher

Workers can emit which files were touched during the test run. This is
used to communicate to the watcher which snapshot file events to ignore
from the current test run, stopping the watcher from running the same
tests repeatedly.

Note that this is only an issue when the `sources` glob has been
customized by the user. The default glob excludes snapshot files.

Files are ignored only once, so subsequent edits of snapshot files
(e.g. by reverting a commit) will cause tests to be rerun.

lib/run-status.js

@@ -73,6 +73,7 @@ class RunStatus extends EventEmitter {
 	}
 	handleTeardown(data) {
 		this.emit('dependencies', data.file, data.dependencies, this);
+		this.emit('touchedFiles', data.touchedFiles);
 	}
 	handleStats(stats) {
 		this.emit('stats', stats, this);

lib/runner.js

@@ -195,7 +195,10 @@ class Runner extends EventEmitter {
 
 	saveSnapshotState() {
 		if (this.snapshots) {
-			this.snapshots.save();
+			const files = this.snapshots.save();
+			if (files) {
+				this.emit('touched', files);
+			}
 		} else if (this.updateSnapshots) {
 			// TODO: There may be unused snapshot files if no test caused the
 			// snapshots to be loaded. Prune them. But not if tests (including hooks!)

lib/snapshot-manager.js

@@ -5,11 +5,11 @@ const fs = require('fs');
 const path = require('path');
 const zlib = require('zlib');
 
+const writeFileAtomic = require('@ava/write-file-atomic');
 const concordance = require('concordance');
 const indentString = require('indent-string');
 const makeDir = require('make-dir');
 const md5Hex = require('md5-hex');
-const writeFileAtomic = require('write-file-atomic');
 
 const concordanceOptions = require('./concordance-options').snapshotManager;
 
@@ -333,7 +333,7 @@ class Manager {
 
 	save() {
 		if (!this.hasChanges) {
-			return;
+			return null;
 		}
 
 		const snapPath = path.join(this.dir, this.snapFile);
@@ -346,8 +346,10 @@ class Manager {
 			generateReport(this.relFile, this.snapFile, this.reportEntries);
 
 		makeDir.sync(this.dir);
-		writeFileAtomic.sync(snapPath, buffer);
-		writeFileAtomic.sync(reportPath, reportBuffer);
+		const tmpSnapPath = writeFileAtomic.sync(snapPath, buffer);
+		const tmpReportPath = writeFileAtomic.sync(reportPath, reportBuffer);
+
+		return [tmpSnapPath, tmpReportPath, snapPath, reportPath];
 	}
 }
 

lib/test-worker.js

@@ -42,10 +42,17 @@ const testPath = opts.file;
 const dependencies = [];
 adapter.installDependencyTracking(dependencies, testPath);
 
+const touchedFiles = new Set();
+
 // Set when main.js is required (since test files should have `require('ava')`).
 let runner = null;
 exports.setRunner = newRunner => {
 	runner = newRunner;
+	runner.on('touched', files => {
+		for (const file of files) {
+			touchedFiles.add(file);
+		}
+	});
 };
 
 require(testPath);
@@ -123,8 +130,9 @@ process.on('ava-teardown', () => {
 
 	// Include dependencies in the final teardown message. This ensures the full
 	// set of dependencies is included no matter how the process exits, unless
-	// it flat out crashes.
-	adapter.send('teardown', {dependencies});
+	// it flat out crashes. Also include any files that AVA touched during the
+	// test run. This allows the watcher to ignore modifications to those files.
+	adapter.send('teardown', {dependencies, touchedFiles: Array.from(touchedFiles)});
 });
 
 process.on('ava-exit', () => {

lib/watcher.js

@@ -116,6 +116,7 @@ class Watcher {
 				}
 			}
 
+			this.touchedFiles.clear();
 			this.busy = api.run(specificFiles || files, {runOnlyExclusive})
 				.then(runStatus => {
 					runStatus.previousFailCount = this.sumPreviousFailures(currentVector);
@@ -130,6 +131,9 @@ class Watcher {
 		this.testDependencies = [];
 		this.trackTestDependencies(api, sources);
 
+		this.touchedFiles = new Set();
+		this.trackTouchedFiles(api);
+
 		this.filesWithExclusiveTests = [];
 		this.trackExclusivity(api);
 
@@ -184,6 +188,15 @@ class Watcher {
 			this.testDependencies.push(new TestDependency(file, sources));
 		}
 	}
+	trackTouchedFiles(api) {
+		api.on('test-run', runStatus => {
+			runStatus.on('touchedFiles', files => {
+				for (const file of files) {
+					this.touchedFiles.add(nodePath.relative(process.cwd(), file));
+				}
+			});
+		});
+	}
 	trackExclusivity(api) {
 		api.on('stats', stats => {
 			this.updateExclusivity(stats.file, stats.hasExclusive);
@@ -284,7 +297,14 @@ class Watcher {
 		const dirtyStates = this.dirtyStates;
 		this.dirtyStates = {};
 
-		const dirtyPaths = Object.keys(dirtyStates);
+		const dirtyPaths = Object.keys(dirtyStates).filter(path => {
+			if (this.touchedFiles.has(path)) {
+				debug('Ignoring known touched file %s', path);
+				this.touchedFiles.delete(path);
+				return false;
+			}
+			return true;
+		});
 		const dirtyTests = dirtyPaths.filter(this.avaFiles.isTest);
 		const dirtySources = diff(dirtyPaths, dirtyTests);
 		const addedOrChangedTests = dirtyTests.filter(path => dirtyStates[path] !== 'unlink');

package.json

@@ -95,6 +95,7 @@
   "dependencies": {
     "@ava/babel-preset-stage-4": "^1.1.0",
     "@ava/babel-preset-transform-test-files": "^3.0.0",
+    "@ava/write-file-atomic": "^2.2.0",
     "@concordance/react": "^0.2.0",
     "ansi-escapes": "^2.0.0",
     "ansi-styles": "^3.1.0",
@@ -170,8 +171,7 @@
     "time-require": "^0.1.2",
     "trim-off-newlines": "^1.0.1",
     "unique-temp-dir": "^1.0.0",
-    "update-notifier": "^2.1.0",
-    "write-file-atomic": "^1.3.4"
+    "update-notifier": "^2.1.0"
   },
   "devDependencies": {
     "cli-table2": "^0.2.0",

test/cli.js

@@ -307,6 +307,32 @@ test('watcher reruns test files when source dependencies change', t => {
 	});
 });
 
+test('watcher does not rerun test files when they write snapshot files', t => {
+	let killed = false;
+
+	const child = execCli(['--verbose', '--watch', '--update-snapshots', 'test.js'], {dirname: 'fixture/snapshots'}, err => {
+		t.ok(killed);
+		t.ifError(err);
+		t.end();
+	});
+
+	let buffer = '';
+	let passedFirst = false;
+	child.stderr.on('data', str => {
+		buffer += str;
+		if (/2 tests passed/.test(buffer) && !passedFirst) {
+			buffer = '';
+			passedFirst = true;
+			setTimeout(() => {
+				child.kill();
+				killed = true;
+			}, 500);
+		} else if (passedFirst && !killed) {
+			t.is(buffer.replace(/\s/g, ''), '');
+		}
+	});
+});
+
 test('`"tap": true` config is ignored when --watch is given', t => {
 	let killed = false;
 

test/fixture/snapshots/package.json

@@ -0,0 +1,5 @@
+{
+	"ava": {
+		"source": "**/*"
+	}
+}