Strings

evaluator/evaluator_test.go

@@ -205,6 +205,10 @@ func TestErrorHandling(t *testing.T) {
 			"foobar",
 			"identifier not found: foobar",
 		},
+		{
+			`"Hello" - "World"`,
+			"unknown operator: STRING - STRING",
+		},
 	}
 
 	for _, tt := range tests {
@@ -294,6 +298,34 @@ func TestClosures(t *testing.T) {
 	testIntegerObject(t, testEval(input), 4)
 }
 
+func TestStringLiteral(t *testing.T) {
+	input := `"Hello World!"`
+
+	evaluated := testEval(input)
+	str, ok := evaluated.(*object.String)
+	if !ok {
+		t.Fatalf("object is not String. got=%T (+%v)", evaluated, evaluated)
+	}
+
+	if str.Value != "Hello World!" {
+		t.Errorf("String has wrong value. got=%q", str.Value)
+	}
+}
+
+func TestStringConcatenation(t *testing.T) {
+	input := `"Hello" + " " + "World!"`
+
+	evaluated := testEval(input)
+	str, ok := evaluated.(*object.String)
+	if !ok {
+		t.Fatalf("object is not String. got=%T (+%v)", evaluated, evaluated)
+	}
+
+	if str.Value != "Hello World!" {
+		t.Errorf("String has wrong value. got=%q", str.Value)
+	}
+}
+
 func testEval(input string) object.Object {
 	l := lexer.New(input)
 	p := parser.New(l)