test info: check file name lengths using 1,2,3,4 byte unicode characters

cmd/test/info/info.go

@@ -91,7 +91,7 @@ type results struct {
 	mu                   sync.Mutex
 	stringNeedsEscaping  map[string]internal.Position
 	controlResults       map[string]internal.ControlResult
-	maxFileLength        int
+	maxFileLength        [4]int
 	canWriteUnnormalized bool
 	canReadUnnormalized  bool
 	canReadRenormalized  bool
@@ -125,7 +125,9 @@ func (r *results) Print() {
 		fmt.Printf("}\n")
 	}
 	if checkLength {
-		fmt.Printf("maxFileLength = %d\n", r.maxFileLength)
+		for i := range r.maxFileLength {
+			fmt.Printf("maxFileLength = %d // for %d byte unicode characters\n", r.maxFileLength[i], i+1)
+		}
 	}
 	if checkNormalization {
 		fmt.Printf("canWriteUnnormalized = %v\n", r.canWriteUnnormalized)
@@ -150,7 +152,7 @@ func (r *results) WriteJSON() {
 		report.ControlCharacters = &r.controlResults
 	}
 	if checkLength {
-		report.MaxFileLength = &r.maxFileLength
+		report.MaxFileLength = &r.maxFileLength[0]
 	}
 	if checkNormalization {
 		report.CanWriteUnnormalized = &r.canWriteUnnormalized
@@ -366,11 +368,27 @@ func (r *results) checkControlsList() {
 }
 
 // find the max file name size we can use
-func (r *results) findMaxLength() {
+func (r *results) findMaxLength(characterLength int) {
+	var character rune
+	switch characterLength {
+	case 1:
+		character = 'a'
+	case 2:
+		character = 'á'
+	case 3:
+		character = '世'
+	case 4:
+		character = '🙂'
+	default:
+		panic("Bad characterLength")
+	}
+	if characterLength != len(string(character)) {
+		panic(fmt.Sprintf("Chose the wrong character length %q is %d not %d", character, len(string(character)), characterLength))
+	}
 	const maxLen = 16 * 1024
-	name := make([]byte, maxLen)
+	name := make([]rune, maxLen)
 	for i := range name {
-		name[i] = 'a'
+		name[i] = character
 	}
 	// Find the first size of filename we can't write
 	i := sort.Search(len(name), func(i int) (fail bool) {
@@ -382,16 +400,20 @@ func (r *results) findMaxLength() {
 		}()
 
 		path := string(name[:i])
-		_, err := r.writeFile(path)
+		o, err := r.writeFile(path)
 		if err != nil {
 			fs.Infof(r.f, "Couldn't write file with name length %d: %v", i, err)
 			return true
 		}
 		fs.Infof(r.f, "Wrote file with name length %d", i)
+		err = o.Remove(context.Background())
+		if err != nil {
+			fs.Errorf(o, "Failed to remove test file")
+		}
 		return false
 	})
-	r.maxFileLength = i - 1
-	fs.Infof(r.f, "Max file length is %d", r.maxFileLength)
+	r.maxFileLength[characterLength-1] = i - 1
+	fs.Infof(r.f, "Max file length is %d when writing %d byte characters %q", r.maxFileLength[characterLength-1], characterLength, character)
 }
 
 func (r *results) checkStreaming() {
@@ -447,7 +469,9 @@ func readInfo(ctx context.Context, f fs.Fs) error {
 		r.checkControls()
 	}
 	if checkLength {
-		r.findMaxLength()
+		for i := range r.maxFileLength {
+			r.findMaxLength(i + 1)
+		}
 	}
 	if checkNormalization {
 		r.checkUTF8Normalization()