Improved code quality

src/token/Tokenize_test.go

@@ -388,6 +388,21 @@ func TestLeadingZero(t *testing.T) {
 	}
 }
 
+func TestRange(t *testing.T) {
+	tokens := token.Tokenize([]byte("a..b"))
+
+	expected := []token.Kind{
+		token.Identifier,
+		token.Range,
+		token.Identifier,
+		token.EOF,
+	}
+
+	for i, kind := range expected {
+		assert.Equal(t, tokens[i].Kind, kind)
+	}
+}
+
 func TestSeparator(t *testing.T) {
 	tokens := token.Tokenize([]byte("a,b,c"))