color: add Equals() method to compare two colors

color.go

@@ -259,6 +259,31 @@ func (c *Color) isNoColorSet() bool {
 	return NoColor
 }
 
+// Equals returns a boolean value indicating whether two colors are equal.
+func (c *Color) Equals(c2 *Color) bool {
+	if len(c.params) != len(c2.params) {
+		return false
+	}
+
+	for _, attr := range c.params {
+		if !c2.attrExists(attr) {
+			return false
+		}
+	}
+
+	return true
+}
+
+func (c *Color) attrExists(a Attribute) bool {
+	for _, attr := range c.params {
+		if attr == a {
+			return true
+		}
+	}
+
+	return false
+}
+
 func boolPtr(v bool) *bool {
 	return &v
 }

color_test.go

@@ -48,6 +48,40 @@ func TestColor(t *testing.T) {
 	}
 }
 
+func TestColorEquals(t *testing.T) {
+	fgblack1 := New(FgBlack)
+	fgblack2 := New(FgBlack)
+	bgblack := New(BgBlack)
+	fgbgblack := New(FgBlack, BgBlack)
+	fgblackbgred := New(FgBlack, BgRed)
+	fgred := New(FgRed)
+	bgred := New(BgRed)
+
+	if !fgblack1.Equals(fgblack2) {
+		t.Error("Two black colors are not equal")
+	}
+
+	if fgblack1.Equals(bgblack) {
+		t.Error("Fg and bg black colors are equal")
+	}
+
+	if fgblack1.Equals(fgbgblack) {
+		t.Error("Fg black equals fg/bg black color")
+	}
+
+	if fgblack1.Equals(fgred) {
+		t.Error("Fg black equals Fg red")
+	}
+
+	if fgblack1.Equals(bgred) {
+		t.Error("Fg black equals Bg red")
+	}
+
+	if fgblack1.Equals(fgblackbgred) {
+		t.Error("Fg black equals fg black bg red")
+	}
+}
+
 func TestNoColor(t *testing.T) {
 	rb := new(bytes.Buffer)
 	Output = rb