NO_COLOR requires a non-empty string

README.md

@@ -7,7 +7,6 @@ suits you.
 
 ![Color](https://user-images.githubusercontent.com/438920/96832689-03b3e000-13f4-11eb-9803-46f4c4de3406.jpg)
 
-
 ## Install
 
 ```bash
@@ -124,17 +123,17 @@ fmt.Println("All text will now be bold magenta.")
 ```
 
 ### Disable/Enable color
- 
+
 There might be a case where you want to explicitly disable/enable color output. the 
 `go-isatty` package will automatically disable color output for non-tty output streams 
 (for example if the output were piped directly to `less`).
 
 The `color` package also disables color output if the [`NO_COLOR`](https://no-color.org) environment
-variable is set (regardless of its value).
+variable is set to a non-empty string.
 
 `Color` has support to disable/enable colors programmatically both globally and
 for single color definitions. For example suppose you have a CLI app and a
-`--no-color` bool flag. You can easily disable the color output with:
+`-no-color` bool flag. You can easily disable the color output with:
 
 ```go
 var flagNoColor = flag.Bool("no-color", false, "Disable color output")
@@ -167,11 +166,10 @@ To output color in GitHub Actions (or other CI systems that support ANSI colors)
 * Save/Return previous values
 * Evaluate fmt.Formatter interface
 
-
 ## Credits
 
- * [Fatih Arslan](https://github.com/fatih)
- * Windows support via @mattn: [colorable](https://github.com/mattn/go-colorable)
+* [Fatih Arslan](https://github.com/fatih)
+* Windows support via @mattn: [colorable](https://github.com/mattn/go-colorable)
 
 ## License
 

color.go

@@ -19,7 +19,7 @@ var (
 	// set (regardless of its value). This is a global option and affects all
 	// colors. For more control over each color block use the methods
 	// DisableColor() individually.
-	NoColor = noColorExists() || os.Getenv("TERM") == "dumb" ||
+	NoColor = noColorIsSet() || os.Getenv("TERM") == "dumb" ||
 		(!isatty.IsTerminal(os.Stdout.Fd()) && !isatty.IsCygwinTerminal(os.Stdout.Fd()))
 
 	// Output defines the standard output of the print functions. By default,
@@ -35,10 +35,9 @@ var (
 	colorsCacheMu sync.Mutex // protects colorsCache
 )
 
-// noColorExists returns true if the environment variable NO_COLOR exists.
-func noColorExists() bool {
-	_, exists := os.LookupEnv("NO_COLOR")
-	return exists
+// noColorIsSet returns true if the environment variable NO_COLOR is set to a non-empty string.
+func noColorIsSet() bool {
+	return os.Getenv("NO_COLOR") != ""
 }
 
 // Color defines a custom color object which is defined by SGR parameters.
@@ -120,7 +119,7 @@ func New(value ...Attribute) *Color {
 		params: make([]Attribute, 0),
 	}
 
-	if noColorExists() {
+	if noColorIsSet() {
 		c.noColor = boolPtr(true)
 	}
 

color_test.go

@@ -183,7 +183,7 @@ func TestNoColor_Env(t *testing.T) {
 		{text: "hwhite", code: FgHiWhite},
 	}
 
-	os.Setenv("NO_COLOR", "")
+	os.Setenv("NO_COLOR", "1")
 	t.Cleanup(func() {
 		os.Unsetenv("NO_COLOR")
 	})
@@ -197,7 +197,41 @@ func TestNoColor_Env(t *testing.T) {
 			t.Errorf("Expecting %s, got '%s'\n", c.text, line)
 		}
 	}
+}
 
+func Test_noColorIsSet(t *testing.T) {
+	tests := []struct {
+		name string
+		act  func()
+		want bool
+	}{
+		{
+			name: "default",
+			act:  func() {},
+			want: false,
+		},
+		{
+			name: "NO_COLOR=1",
+			act:  func() { os.Setenv("NO_COLOR", "1") },
+			want: true,
+		},
+		{
+			name: "NO_COLOR=",
+			act:  func() { os.Setenv("NO_COLOR", "") },
+			want: false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Cleanup(func() {
+				os.Unsetenv("NO_COLOR")
+			})
+			tt.act()
+			if got := noColorIsSet(); got != tt.want {
+				t.Errorf("noColorIsSet() = %v, want %v", got, tt.want)
+			}
+		})
+	}
 }
 
 func TestColorVisual(t *testing.T) {