feat: prism tests watcher

cmd/root.go

@@ -19,7 +19,7 @@ var (
 var rootCmd = &cobra.Command{
 	Use:   "prism",
 	Short: "Prism is a wrapper around go test to make it simple and beautiful",
-	Long: internal.Header() + "\n\n" + `Prism is a wrapper around Go's built in test command that aims to make it beautiful and organized. 
+	Long: internal.Header() + "\n\n" + `Prism is a wrapper around Go's built in test command that aims to make it beautiful and organized.
 
 Issues? Requests? Feedback? Let me know! -- github.com/DaltonSW/prism`,
 	Args: cobra.ArbitraryArgs,
@@ -29,6 +29,10 @@ Issues? Requests? Feedback? Let me know! -- github.com/DaltonSW/prism`,
 		}
 	},
 	Run: func(cmd *cobra.Command, args []string) {
+		if internal.GlobalConfig.Watch {
+			internal.Watch(args)
+			return
+		}
 		internal.Execute(args)
 	},
 }
@@ -51,6 +55,7 @@ func init() {
 	rootCmd.PersistentFlags().BoolVarP(&internal.GlobalConfig.Verbose, "verbose", "v", internal.GlobalConfig.Verbose, "Include test sub-output")
 	rootCmd.PersistentFlags().BoolVarP(&internal.GlobalConfig.OnlyFails, "only-fails", "f", internal.GlobalConfig.OnlyFails, "Only run failing tests")
 	rootCmd.PersistentFlags().BoolVar(&internal.GlobalConfig.NoBar, "no-bar", internal.GlobalConfig.NoBar, "Hide the summary bar at the end of test output")
+	rootCmd.PersistentFlags().BoolVarP(&internal.GlobalConfig.Watch, "watch", "w", internal.GlobalConfig.Watch, "Watch for file changes and rerun tests")
 
 	rootCmd.PersistentFlags().BoolVar(&internal.GlobalConfig.NoColor, "no-color", internal.GlobalConfig.NoColor, "Disable color output entirely")
 	rootCmd.PersistentFlags().BoolVar(&internal.GlobalConfig.ShowColor, "color", internal.GlobalConfig.ShowColor, "Force color output, overridding NO_COLOR environment variable")

go.mod

@@ -6,6 +6,10 @@ require (
 	github.com/charmbracelet/fang v0.4.2
 	github.com/charmbracelet/lipgloss/v2 v2.0.0-beta.3.0.20250917201909-41ff0bf215ea
 	github.com/charmbracelet/log v0.4.2
+	github.com/charmbracelet/x/ansi v0.10.1
+	github.com/charmbracelet/x/term v0.2.1
+	github.com/fsnotify/fsnotify v1.10.1
+	github.com/sabhiram/go-gitignore v0.0.0-20210923224102-525f6e181f06
 	github.com/spf13/cobra v1.9.1
 	github.com/yarlson/pin v0.9.1
 )
@@ -15,10 +19,8 @@ require (
 	github.com/charmbracelet/colorprofile v0.3.2 // indirect
 	github.com/charmbracelet/lipgloss v1.1.0 // indirect
 	github.com/charmbracelet/ultraviolet v0.0.0-20250915111650-81d4262876ef // indirect
-	github.com/charmbracelet/x/ansi v0.10.1 // indirect
 	github.com/charmbracelet/x/cellbuf v0.0.13 // indirect
 	github.com/charmbracelet/x/exp/charmtone v0.0.0-20250603201427-c31516f43444 // indirect
-	github.com/charmbracelet/x/term v0.2.1 // indirect
 	github.com/charmbracelet/x/termios v0.1.1 // indirect
 	github.com/charmbracelet/x/windows v0.2.2 // indirect
 	github.com/go-logfmt/logfmt v0.6.0 // indirect

go.sum

@@ -29,8 +29,11 @@ github.com/charmbracelet/x/termios v0.1.1/go.mod h1:rB7fnv1TgOPOyyKRJ9o+AsTU/vK5
 github.com/charmbracelet/x/windows v0.2.2 h1:IofanmuvaxnKHuV04sC0eBy/smG6kIKrWG2/jYn2GuM=
 github.com/charmbracelet/x/windows v0.2.2/go.mod h1:/8XtdKZzedat74NQFn0NGlGL4soHB0YQZrETF96h75k=
 github.com/cpuguy83/go-md2man/v2 v2.0.6/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/fsnotify/fsnotify v1.10.1 h1:b0/UzAf9yR5rhf3RPm9gf3ehBPpf0oZKIjtpKrx59Ho=
+github.com/fsnotify/fsnotify v1.10.1/go.mod h1:TLheqan6HD6GBK6PrDWyDPBaEV8LspOxvPSjC+bVfgo=
 github.com/go-logfmt/logfmt v0.6.0 h1:wGYYu3uicYdqXVgoYbvnkrPVXkuLM1p1ifugDMEdRi4=
 github.com/go-logfmt/logfmt v0.6.0/go.mod h1:WYhtIu8zTZfxdn5+rREduYbwxfcBr/Vr6KEVveWlfTs=
 github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
@@ -59,11 +62,15 @@ github.com/rivo/uniseg v0.2.0/go.mod h1:J6wj4VEh+S6ZtnVlnTBMWIodfgj8LQOQFoIToxlJ
 github.com/rivo/uniseg v0.4.7 h1:WUdvkW8uEhrYfLC4ZzdpI2ztxP1I582+49Oc5Mq64VQ=
 github.com/rivo/uniseg v0.4.7/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/sabhiram/go-gitignore v0.0.0-20210923224102-525f6e181f06 h1:OkMGxebDjyw0ULyrTYWeN0UNCCkmCWfjPnIA2W6oviI=
+github.com/sabhiram/go-gitignore v0.0.0-20210923224102-525f6e181f06/go.mod h1:+ePHsJ1keEjQtpvf9HHw0f4ZeJ0TLRsxhunSI2hYJSs=
 github.com/spf13/cobra v1.9.1 h1:CXSaggrXdbHK9CF+8ywj8Amf7PBRmPCOJugH954Nnlo=
 github.com/spf13/cobra v1.9.1/go.mod h1:nDyEzZ8ogv936Cinf6g1RU9MRY64Ir93oCnqb9wxYW0=
 github.com/spf13/pflag v1.0.6/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 github.com/spf13/pflag v1.0.10 h1:4EBh2KAYBwaONj6b2Ye1GiHfwjqyROoF4RwYO+vPwFk=
 github.com/spf13/pflag v1.0.10/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
 github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
 github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e h1:JVG44RsyaB9T2KIHavMF/ppJZNG9ZpyihvCd0w101no=
@@ -80,5 +87,6 @@ golang.org/x/sys v0.36.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
 golang.org/x/text v0.28.0 h1:rhazDwis8INMIwQ4tpjLDzUhx6RlXqZNPEM0huQojng=
 golang.org/x/text v0.28.0/go.mod h1:U8nCwOR8jO/marOQ0QbDiOngZVEBB7MAiitBuMjXiNU=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

internal/config.go

@@ -26,6 +26,7 @@ type Config struct {
 	NoBar     bool `json:"no_bar"`
 	NoColor   bool `json:"no_color"`
 	ShowColor bool `json:"show_color"`
+	Watch     bool `json:"watch"`
 }
 
 // GlobalConfig holds the active configuration for the current process.

internal/watcher.go

@@ -0,0 +1,218 @@
+package internal
+
+import (
+	"fmt"
+	"io/fs"
+	"os"
+	"os/signal"
+	"path/filepath"
+	"strings"
+	"syscall"
+	"time"
+
+	"github.com/charmbracelet/lipgloss/v2"
+	"github.com/charmbracelet/x/ansi"
+	"github.com/charmbracelet/x/term"
+	"github.com/fsnotify/fsnotify"
+	ignore "github.com/sabhiram/go-gitignore"
+)
+
+const watchDebounce = 200 * time.Millisecond
+
+var watchStatusStyle = lipgloss.NewStyle().Foreground(lipgloss.Color("#666666"))
+
+// Watch runs the initial test pass then enters a debounced rerun loop keyed on .go file changes. `r` force rerun, `q` or ctrl+c quits.
+func Watch(args []string) {
+	scope := "./..."
+	if len(args) > 0 {
+		scope = strings.Join(args, " ")
+	}
+	fmt.Printf("[watch] watching %s\n", scope)
+
+	watcher, err := fsnotify.NewWatcher()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "watcher: %v\n", err)
+		return
+	}
+	defer watcher.Close()
+
+	matcher := loadIgnore(".")
+	if err := watchRecursive(watcher, ".", matcher, nil); err != nil {
+		fmt.Fprintf(os.Stderr, "watch setup: %v\n", err)
+	}
+
+	// Pre-render ui strings to avoid allocations during the run loop.
+	status := watchStatusStyle.Render("[watch] idle · press r to rerun · q to quit")
+	clear := ansi.CursorHomePosition + ansi.EraseEntireScreen + ansi.EraseEntireDisplay
+
+	Execute(args)
+	fmt.Println(status)
+
+	fd := os.Stdin.Fd()
+	oldState, err := term.MakeRaw(fd)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "raw mode: %v\n", err)
+		return
+	}
+	defer term.Restore(fd, oldState)
+
+	sigCh := make(chan os.Signal, 1)
+	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
+	defer signal.Stop(sigCh)
+
+	keyCh := make(chan byte, 1)
+	go readKeys(keyCh)
+
+	rerun := func(trigger string) {
+		_ = term.Restore(fd, oldState)
+		fmt.Printf("%s[watch] trigger: %s\n\n", clear, trigger)
+		Execute(args)
+		fmt.Println(status)
+		if _, err := term.MakeRaw(fd); err != nil {
+			fmt.Fprintf(os.Stderr, "raw mode: %v\n", err)
+		}
+	}
+
+	var (
+		timer       *time.Timer
+		timerC      <-chan time.Time
+		lastTrigger string
+	)
+
+	schedule := func(trigger string) {
+		lastTrigger = trigger
+		if timer == nil {
+			timer = time.NewTimer(watchDebounce)
+		} else {
+			if !timer.Stop() {
+				select {
+				case <-timer.C:
+				default:
+				}
+			}
+			timer.Reset(watchDebounce)
+		}
+		timerC = timer.C
+	}
+
+	for {
+		select {
+		case ev, ok := <-watcher.Events:
+			if !ok {
+				return
+			}
+			if ev.Has(fsnotify.Create) {
+				if info, err := os.Stat(ev.Name); err == nil && info.IsDir() {
+					// fsnotify only sees changes from here on; a directory
+					// that arrived with files already inside it needs a manual nudge.
+					var foundGoFile string
+					err := watchRecursive(watcher, ev.Name, matcher, func(p string) {
+						if foundGoFile == "" {
+							foundGoFile = p
+						}
+					})
+					if err != nil {
+						fmt.Fprintf(os.Stderr, "watch add: %v\n", err)
+					}
+					if foundGoFile != "" {
+						schedule(filepath.Base(foundGoFile))
+					}
+				}
+				continue
+			}
+			if !strings.HasSuffix(ev.Name, ".go") {
+				continue
+			}
+			schedule(filepath.Base(ev.Name))
+
+		case <-timerC:
+			timer, timerC = nil, nil
+			rerun(lastTrigger)
+
+		case b, ok := <-keyCh:
+			if !ok {
+				return
+			}
+			switch b {
+			case 'r', 'R':
+				if timer != nil {
+					timer.Stop()
+					timer, timerC = nil, nil
+				}
+				rerun("manual")
+			case 'q', 'Q', 0x03: // Ctrl+C
+				return
+			}
+
+		case <-sigCh:
+			return
+
+		case err, ok := <-watcher.Errors:
+			if !ok {
+				return
+			}
+			fmt.Fprintf(os.Stderr, "watch error: %v\n", err)
+		}
+	}
+}
+
+// readKeys streams bytes from stdin until it hits EOF or a read error.
+func readKeys(out chan<- byte) {
+	defer close(out)
+	b := make([]byte, 1)
+	for {
+		if _, err := os.Stdin.Read(b); err != nil {
+			return
+		}
+		out <- b[0]
+	}
+}
+
+func loadIgnore(root string) *ignore.GitIgnore {
+	patterns := []string{".git/"}
+	path := filepath.Join(root, ".gitignore")
+	if data, err := os.ReadFile(path); err == nil {
+		for line := range strings.SplitSeq(string(data), "\n") {
+			if line != "" {
+				patterns = append(patterns, line)
+			}
+		}
+	}
+	return ignore.CompileIgnoreLines(patterns...)
+}
+
+// isIgnored reports whether path matches the .gitignore patterns. isDir
+// must reflect whether path is a directory, since gitignore patterns can
+// be directory only.
+func isIgnored(path string, isDir bool, matcher *ignore.GitIgnore) bool {
+	if matcher == nil {
+		return false
+	}
+	if isDir {
+		// Ensure trailing slash for directory matching
+		if !strings.HasSuffix(path, string(filepath.Separator)) {
+			path += string(filepath.Separator)
+		}
+	}
+	return matcher.MatchesPath(path)
+}
+
+// watchRecursive adds directories to the watcher. If onGoFile is provided,
+// it will call it with the first .go file it encounters.
+func watchRecursive(w *fsnotify.Watcher, root string, matcher *ignore.GitIgnore, onGoFile func(string)) error {
+	return filepath.WalkDir(root, func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return nil
+		}
+		if d.IsDir() {
+			if isIgnored(path, true, matcher) {
+				return filepath.SkipDir
+			}
+			return w.Add(path)
+		}
+		if onGoFile != nil && strings.HasSuffix(path, ".go") && !isIgnored(path, false, matcher) {
+			onGoFile(path)
+		}
+		return nil
+	})
+}