Properly handle single arg calls to helper funcs (#40)

* Properly handle single arg calls to helper funcs

color.go

@@ -345,6 +345,11 @@ func Cyan(format string, a ...interface{}) { printColor(format, FgCyan, a...) }
 func White(format string, a ...interface{}) { printColor(format, FgWhite, a...) }
 
 func printColor(format string, p Attribute, a ...interface{}) {
+	if len(a) == 0 {
+		a = append(a, format)
+		format = "%s"
+	}
+
 	if !strings.HasSuffix(format, "\n") {
 		format += "\n"
 	}
@@ -353,50 +358,44 @@ func printColor(format string, p Attribute, a ...interface{}) {
 	c.Printf(format, a...)
 }
 
+func printString(format string, p Attribute, a ...interface{}) string {
+	if len(a) == 0 {
+		a = append(a, format)
+		format = "%s"
+	}
+	return New(p).SprintfFunc()(format, a...)
+}
+
 // BlackString is an convenient helper function to return a string with black
 // foreground.
-func BlackString(format string, a ...interface{}) string {
-	return New(FgBlack).SprintfFunc()(format, a...)
-}
+func BlackString(format string, a ...interface{}) string { return printString(format, FgBlack, a...) }
 
 // RedString is an convenient helper function to return a string with red
 // foreground.
-func RedString(format string, a ...interface{}) string {
-	return New(FgRed).SprintfFunc()(format, a...)
-}
+func RedString(format string, a ...interface{}) string { return printString(format, FgRed, a...) }
 
 // GreenString is an convenient helper function to return a string with green
 // foreground.
-func GreenString(format string, a ...interface{}) string {
-	return New(FgGreen).SprintfFunc()(format, a...)
-}
+func GreenString(format string, a ...interface{}) string { return printString(format, FgGreen, a...) }
 
 // YellowString is an convenient helper function to return a string with yellow
 // foreground.
-func YellowString(format string, a ...interface{}) string {
-	return New(FgYellow).SprintfFunc()(format, a...)
-}
+func YellowString(format string, a ...interface{}) string { return printString(format, FgYellow, a...) }
 
 // BlueString is an convenient helper function to return a string with blue
 // foreground.
-func BlueString(format string, a ...interface{}) string {
-	return New(FgBlue).SprintfFunc()(format, a...)
-}
+func BlueString(format string, a ...interface{}) string { return printString(format, FgBlue, a...) }
 
 // MagentaString is an convenient helper function to return a string with magenta
 // foreground.
 func MagentaString(format string, a ...interface{}) string {
-	return New(FgMagenta).SprintfFunc()(format, a...)
+	return printString(format, FgMagenta, a...)
 }
 
 // CyanString is an convenient helper function to return a string with cyan
 // foreground.
-func CyanString(format string, a ...interface{}) string {
-	return New(FgCyan).SprintfFunc()(format, a...)
-}
+func CyanString(format string, a ...interface{}) string { return printString(format, FgCyan, a...) }
 
 // WhiteString is an convenient helper function to return a string with white
 // foreground.
-func WhiteString(format string, a ...interface{}) string {
-	return New(FgWhite).SprintfFunc()(format, a...)
-}
+func WhiteString(format string, a ...interface{}) string { return printString(format, FgWhite, a...) }

color_test.go

@@ -224,3 +224,54 @@ func TestColorVisual(t *testing.T) {
 	fmt.Fprintln(Output, CyanString("cyan"))
 	fmt.Fprintln(Output, WhiteString("white"))
 }
+
+func TestNoFormat(t *testing.T) {
+	fmt.Printf("%s   %%s = ", BlackString("Black"))
+	Black("%s")
+
+	fmt.Printf("%s     %%s = ", RedString("Red"))
+	Red("%s")
+
+	fmt.Printf("%s   %%s = ", GreenString("Green"))
+	Green("%s")
+
+	fmt.Printf("%s  %%s = ", YellowString("Yellow"))
+	Yellow("%s")
+
+	fmt.Printf("%s    %%s = ", BlueString("Blue"))
+	Blue("%s")
+
+	fmt.Printf("%s %%s = ", MagentaString("Magenta"))
+	Magenta("%s")
+
+	fmt.Printf("%s    %%s = ", CyanString("Cyan"))
+	Cyan("%s")
+
+	fmt.Printf("%s   %%s = ", WhiteString("White"))
+	White("%s")
+}
+
+func TestNoFormatString(t *testing.T) {
+	tests := []struct {
+		f      func(string, ...interface{}) string
+		format string
+		args   []interface{}
+		want   string
+	}{
+		{BlackString, "%s", nil, "\x1b[30m%s\x1b[0m"},
+		{RedString, "%s", nil, "\x1b[31m%s\x1b[0m"},
+		{GreenString, "%s", nil, "\x1b[32m%s\x1b[0m"},
+		{YellowString, "%s", nil, "\x1b[33m%s\x1b[0m"},
+		{BlueString, "%s", nil, "\x1b[34m%s\x1b[0m"},
+		{MagentaString, "%s", nil, "\x1b[35m%s\x1b[0m"},
+		{CyanString, "%s", nil, "\x1b[36m%s\x1b[0m"},
+		{WhiteString, "%s", nil, "\x1b[37m%s\x1b[0m"},
+	}
+
+	for i, test := range tests {
+		s := fmt.Sprintf("%s", test.f(test.format, test.args...))
+		if s != test.want {
+			t.Errorf("[%d] want: %q, got: %q", i, test.want, s)
+		}
+	}
+}