Add command for updating snapshots in watch mode (#1413)

Author: efegurkan

api.js

@@ -60,6 +60,10 @@ class Api extends EventEmitter {
 precompiled[resolvedfpath] = hash;
 
 const options = Object.assign({}, this.options, {precompiled});
+if (runStatus.updateSnapshots) {
+// Don't use in Object.assign() since it'll override options.updateSnapshots even when false.
+options.updateSnapshots = true;
+}
 const emitter = fork(file, options, execArgv);
 runStatus.observeFork(emitter);
 
@@ -137,7 +141,8 @@ class Api extends EventEmitter {
 runOnlyExclusive: options.runOnlyExclusive,
 prefixTitles: this.options.explicitTitles || files.length > 1,
 base: path.relative(process.cwd(), commonPathPrefix(files)) + path.sep,
-failFast: this.options.failFast
+failFast: this.options.failFast,
+updateSnapshots: options.updateSnapshots
 });
 
 this.emit('test-run', runStatus, files);

docs/recipes/watch-mode.md

@@ -91,6 +91,10 @@ If you run AVA in your CI with watch mode, the execution will exit with an error
 
 You can quickly rerun all tests by typing <kbd>r</kbd> on the console, followed by <kbd>Enter</kbd>.
 
+## Updating snapshots
+
+You can update failing snapshots by typing <kbd>u</kbd> on the console, followed by <kbd>Enter</kbd>.
+
 ## Debugging
 
 Sometimes watch mode does something surprising like rerunning all tests when you thought only a single test would be run. To see its reasoning you can enable a debug mode. This will work best with the verbose reporter:

lib/run-status.js

@@ -40,6 +40,7 @@ class RunStatus extends EventEmitter {
 this.stats = [];
 this.tests = [];
 this.failFastEnabled = opts.failFast || false;
+this.updateSnapshots = opts.updateSnapshots || false;
 
 autoBind(this);
 }

lib/watcher.js

@@ -84,7 +84,8 @@ class Watcher {
 
 this.clearLogOnNextRun = true;
 this.runVector = 0;
-this.run = specificFiles => {
+this.previousFiles = files;
+this.run = (specificFiles, updateSnapshots) => {
 if (this.runVector > 0) {
 const cleared = this.clearLogOnNextRun && logger.clear();
 if (!cleared) {
@@ -117,7 +118,8 @@ class Watcher {
 }
 
 this.touchedFiles.clear();
-this.busy = api.run(specificFiles || files, {runOnlyExclusive})
+this.previousFiles = specificFiles || files;
+this.busy = api.run(this.previousFiles, {runOnlyExclusive, updateSnapshots: updateSnapshots === true})
 .then(runStatus => {
 runStatus.previousFailCount = this.sumPreviousFailures(currentVector);
 logger.finish(runStatus);
@@ -273,7 +275,7 @@ class Watcher {
 
 stdin.on('data', data => {
 data = data.trim().toLowerCase();
-if (data !== 'r' && data !== 'rs') {
+if (data !== 'r' && data !== 'rs' && data !== 'u') {
 return;
 }
 
@@ -285,14 +287,22 @@ class Watcher {
 // the busy promise to fulfil
 this.debouncer.cancel();
 this.clearLogOnNextRun = false;
-this.rerunAll();
+if (data === 'u') {
+this.updatePreviousSnapshots();
+} else {
+this.rerunAll();
+}
 });
 });
 }
 rerunAll() {
 this.dirtyStates = {};
 this.run();
 }
+updatePreviousSnapshots() {
+this.dirtyStates = {};
+this.run(this.previousFiles, true);
+}
 runAfterChanges() {
 const dirtyStates = this.dirtyStates;
 this.dirtyStates = {};