restructure inotify package and add some tests

internal/inotify/walker/walker.go

@@ -0,0 +1,52 @@
+package walker
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+)
+
+const maxInt = int(^uint(0) >> 1)
+
+func Walk(root string, depth int, errCh chan error) (dirCh chan string, doneCh chan struct{}) {
+	if depth < 0 {
+		depth = maxInt
+	}
+	dirCh = make(chan string)
+	doneCh = make(chan struct{})
+
+	go func() {
+		descent(root, depth-1, dirCh, errCh, doneCh)
+		close(dirCh)
+	}()
+	return dirCh, doneCh
+}
+
+func descent(dir string, depth int, dirCh chan string, errCh chan error, doneCh chan struct{}) {
+	_, err := os.Stat(dir)
+	if err != nil {
+		errCh <- fmt.Errorf("Can't walk directory %s: %v", dir, err)
+		return
+	}
+	select {
+	case dirCh <- dir:
+	case <-doneCh:
+		return
+	}
+	if depth < 0 {
+		return
+	}
+
+	ls, err := ioutil.ReadDir(dir)
+	if err != nil {
+		errCh <- fmt.Errorf("opening dir %s: %v", dir, err)
+	}
+
+	for _, e := range ls {
+		if e.IsDir() {
+			newDir := filepath.Join(dir, e.Name())
+			descent(newDir, depth-1, dirCh, errCh, doneCh)
+		}
+	}
+}

internal/inotify/walker/walker_test.go

@@ -0,0 +1,84 @@
+package walker
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+)
+
+func TestWalk(t *testing.T) {
+	tests := []struct {
+		root   string
+		depth  int
+		errCh  chan error
+		result []string
+		errs   []string
+	}{
+		{root: "testdata", depth: 999, errCh: newErrCh(), result: []string{
+			"testdata",
+			"testdata/subdir",
+			"testdata/subdir/subsubdir",
+		}, errs: make([]string, 0)},
+		{root: "testdata", depth: -1, errCh: newErrCh(), result: []string{
+			"testdata",
+			"testdata/subdir",
+			"testdata/subdir/subsubdir",
+		}, errs: []string{}},
+		{root: "testdata", depth: 1, errCh: newErrCh(), result: []string{
+			"testdata",
+			"testdata/subdir",
+		}, errs: []string{}},
+		{root: "testdata", depth: 0, errCh: newErrCh(), result: []string{
+			"testdata",
+		}, errs: []string{}},
+		{root: "testdata/subdir", depth: 1, errCh: newErrCh(), result: []string{
+			"testdata/subdir",
+			"testdata/subdir/subsubdir",
+		}, errs: []string{}},
+		{root: "testdata/non-existing-dir", depth: 1, errCh: newErrCh(), result: []string{}, errs: []string{"Can't walk directory testdata/non-existing-dir"}},
+	}
+
+	for i, tt := range tests {
+		dirCh, doneCh := Walk(tt.root, tt.depth, tt.errCh)
+		dirs, errs := getAllDirsAndErrors(dirCh, tt.errCh)
+
+		if !reflect.DeepEqual(dirs, tt.result) {
+			t.Fatalf("[%d] Wrong number of dirs found: %+v", i, dirs)
+		}
+		if !reflect.DeepEqual(errs, tt.errs) {
+			t.Fatalf("[%d] Wrong number of errs found: %+v vs %+v", i, errs, tt.errs)
+		}
+		close(doneCh)
+	}
+
+}
+
+func getAllDirsAndErrors(dirCh chan string, errCh chan error) ([]string, []string) {
+	dirs := make([]string, 0)
+	errs := make([]string, 0)
+
+	doneDirsCh := make(chan struct{})
+	go func() {
+		for d := range dirCh {
+			dirs = append(dirs, d)
+		}
+		close(errCh)
+		close(doneDirsCh)
+	}()
+
+	doneErrsCh := make(chan struct{})
+	go func() {
+		for err := range errCh {
+			tokens := strings.SplitN(err.Error(), ":", 2)
+			errs = append(errs, tokens[0])
+		}
+		close(doneErrsCh)
+	}()
+	<-doneDirsCh
+	<-doneErrsCh
+	return dirs, errs
+}
+
+func newErrCh() chan error {
+	return make(chan error)
+}