From cdd0de15cffeb2b32b8768194fed50235a345698 Mon Sep 17 00:00:00 2001
From: Daniel Nephin <dnephin@gmail.com>
Date: Fri, 28 May 2021 15:06:35 -0400
Subject: [PATCH] Add 'l' action for watch mode

---
 README.md                         |  7 ++++--
 internal/filewatcher/term_unix.go |  3 +++
 internal/filewatcher/watch.go     | 36 +++++++++++++++++++++++--------
 3 files changed, 35 insertions(+), 11 deletions(-)

diff --git a/README.md b/README.md
index cc52fe3c..f7ffe4c4 100644
--- a/README.md
+++ b/README.md
@@ -309,8 +309,8 @@ When the `--watch` flag is set, `gotestsum` will watch directories using
 [file system notifications](https://pkg.go.dev/github.com/fsnotify/fsnotify).
 When a Go file in one of those directories is modified, `gotestsum` will run the
 tests for the package which contains the changed file. By default all
-directories under the current directory will be watched. Use the `--packages` flag
-to specify a different list.
+directories with at least one file with a `.go` extension, under the current
+directory will be watched. Use the `--packages` flag to specify a different list.
 
 While in watch mode, pressing some keys will perform an action:
 
@@ -321,6 +321,9 @@ While in watch mode, pressing some keys will perform an action:
   breakpoints can be added with [`runtime.Breakpoint`](https://golang.org/pkg/runtime/#Breakpoint)
   or by using the delve command prompt.
 * `a` will run tests for all packages, by using `./...` as the package selector.
+* `l` will scan the directory list again, and if there are any new directories
+  which contain a file with a `.go` extension, they will be added to the watch
+  list.
 
 Note that [delve] must be installed in order to use debug (`d`).
 
diff --git a/internal/filewatcher/term_unix.go b/internal/filewatcher/term_unix.go
index 303d6bcc..c9e2e76f 100644
--- a/internal/filewatcher/term_unix.go
+++ b/internal/filewatcher/term_unix.go
@@ -83,6 +83,9 @@ func (r *redoHandler) Run(ctx context.Context) {
 		case 'a':
 			chResume = make(chan struct{})
 			r.ch <- RunOptions{resume: chResume, PkgPath: "./..."}
+		case 'l':
+			chResume = make(chan struct{})
+			r.ch <- RunOptions{resume: chResume, reloadPaths: true}
 		case '\n':
 			fmt.Println()
 			continue
diff --git a/internal/filewatcher/watch.go b/internal/filewatcher/watch.go
index e80c4e5d..9db8b118 100644
--- a/internal/filewatcher/watch.go
+++ b/internal/filewatcher/watch.go
@@ -16,27 +16,26 @@ import (
 const maxDepth = 7
 
 type RunOptions struct {
-	PkgPath string
-	Debug   bool
-	resume  chan struct{}
+	PkgPath     string
+	Debug       bool
+	resume      chan struct{}
+	reloadPaths bool
 }
 
+// Watch dirs for filesystem events, and run tests when .go files are saved.
+// nolint: gocyclo
 func Watch(dirs []string, run func(opts RunOptions) error) error {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
-	toWatch := findAllDirs(dirs, maxDepth)
 	watcher, err := fsnotify.NewWatcher()
 	if err != nil {
 		return fmt.Errorf("failed to create file watcher: %w", err)
 	}
 	defer watcher.Close() // nolint: errcheck // always returns nil error
 
-	fmt.Printf("Watching %v directories. Use Ctrl-c to to stop a run or exit.\n", len(toWatch))
-	for _, dir := range toWatch {
-		if err = watcher.Add(dir); err != nil {
-			return fmt.Errorf("failed to watch directory %v: %w", dir, err)
-		}
+	if err := loadPaths(watcher, dirs); err != nil {
+		return err
 	}
 
 	timer := time.NewTimer(maxIdleTime)
@@ -55,6 +54,14 @@ func Watch(dirs []string, run func(opts RunOptions) error) error {
 		case opts := <-redo.Ch():
 			resetTimer(timer)
 
+			if opts.reloadPaths {
+				if err := loadPaths(watcher, dirs); err != nil {
+					return err
+				}
+				close(opts.resume)
+				continue
+			}
+
 			redo.ResetTerm()
 			if err := h.runTests(opts); err != nil {
 				return fmt.Errorf("failed to rerun tests for %v: %v", opts.PkgPath, err)
@@ -89,6 +96,17 @@ func resetTimer(timer *time.Timer) {
 	timer.Reset(maxIdleTime)
 }
 
+func loadPaths(watcher *fsnotify.Watcher, dirs []string) error {
+	toWatch := findAllDirs(dirs, maxDepth)
+	fmt.Printf("Watching %v directories. Use Ctrl-c to to stop a run or exit.\n", len(toWatch))
+	for _, dir := range toWatch {
+		if err := watcher.Add(dir); err != nil {
+			return fmt.Errorf("failed to watch directory %v: %w", dir, err)
+		}
+	}
+	return nil
+}
+
 func findAllDirs(dirs []string, maxDepth int) []string {
 	if len(dirs) == 0 {
 		dirs = []string{"./..."}