support NO_COLOR

rezamt · Apr 17, 2020 · 2131b8c · 2131b8c
1 parent 909e6f7
commit 2131b8c
Show file tree

Hide file tree

Showing 2 changed files with 27 additions and 4 deletions.
diff --git a/pkg/internal/env/term.go b/pkg/internal/env/term.go
@@ -45,16 +45,29 @@ func IsTerminal(w io.Writer) bool {
 // IsSmartTerminal returns true if the writer w is a terminal AND
 // we think that the terminal is smart enough to use VT escape codes etc.
 func IsSmartTerminal(w io.Writer) bool {
-	return isSmartTerminal(w, runtime.GOOS, os.Getenv)
+	return isSmartTerminal(w, runtime.GOOS, os.LookupEnv)
 }
 
-func isSmartTerminal(w io.Writer, GOOS string, getenv func(string) string) bool {
+func isSmartTerminal(w io.Writer, GOOS string, lookupEnv func(string) (string, bool)) bool {
 	// Not smart if it's not a tty
 	if !IsTerminal(w) {
 		return false
 	}
 
+	// getenv helper for when we only care about the value
+	getenv := func(e string) string {
+		v, _ := lookupEnv(e)
+		return v
+	}
+
+	// Explicit request for no ANSI escape codes
+	// https://no-color.org/
+	if _, set := lookupEnv("NO_COLOR"); set {
+		return false
+	}
+
 	// Explicitly dumb terminals are not smart
+	// https://en.wikipedia.org/wiki/Computer_terminal#Dumb_terminals
 	if getenv("TERM") == "dumb" {
 		return false
 	}

diff --git a/pkg/internal/env/term_test.go b/pkg/internal/env/term_test.go
@@ -98,6 +98,15 @@ func TestIsSmartTerminal(t *testing.T) {
 			IsSmart: false,
 			Writer:  &testFakeTTY{},
 		},
+		{
+			Name: "tty, NO_COLOR=",
+			FakeEnv: map[string]string{
+				"NO_COLOR": "",
+			},
+			GOOS:    "linux",
+			IsSmart: false,
+			Writer:  &testFakeTTY{},
+		},
 		{
 			Name: "tty, Travis CI",
 			FakeEnv: map[string]string{
@@ -112,8 +121,9 @@ func TestIsSmartTerminal(t *testing.T) {
 	for _, tc := range cases {
 		tc := tc // capture tc
 		t.Run(tc.Name, func(t *testing.T) {
-			res := isSmartTerminal(tc.Writer, tc.GOOS, func(s string) string {
-				return tc.FakeEnv[s]
+			res := isSmartTerminal(tc.Writer, tc.GOOS, func(s string) (string, bool) {
+				k, set := tc.FakeEnv[s]
+				return k, set
 			})
 			assert.BoolEqual(t, tc.IsSmart, res)
 		})