Monkey/evaluator/evaluator_test.go

package evaluator

import (
	"github/runnignwater/monkey/lexer"
	"github/runnignwater/monkey/object"
	"github/runnignwater/monkey/parser"
	"testing"
)

func TestEvalIntegerExpression(t *testing.T) {
	tests := []struct {
		input    string
		expected int64
	}{
		{"5", 5},
		{"10", 10},
		{"-5", -5},
		{"-10", -10},
		{"5+5+5+5-10", 10},
		{"2*2*2*2*2", 32},
		{"-50+100+-50", 0},
	}

	for _, tt := range tests {
		evaluated := testEval(tt.input)
		testIntegerObject(t, evaluated, tt.expected)
	}
}

func TestEvalBooleanExpression(t *testing.T) {
	tests := []struct {
		input    string
		expected bool
	}{
		{"true", true},
		{"false", false},
		{"1 < 2", true},
		{"1 > 2", false},
		{"1 == 1", true},
		{"1 != 1", false},
		{"1 == 2", false},
		{"1 != 2", true},
		{"true == true", true},
		{"false == false", true},
		{"(1 < 2) == true", true},
	}

	for _, tt := range tests {
		evaluated := testEval(tt.input)
		testBooleanObject(t, evaluated, tt.expected)
	}
}

func TestBangOperator(t *testing.T) {
	tests := []struct {
		input    string
		expected bool
	}{
		{"!true", false},
		{"!false", true},
		{"!5", false},
		{"!!true", true},
		{"!!false", false},
		{"!!5", true},
	}

	for _, tt := range tests {
		evaluated := testEval(tt.input)
		testBooleanObject(t, evaluated, tt.expected)
	}
}

func TestIfElseExpression(t *testing.T) {
	tests := []struct {
		input    string
		expected interface{}
	}{
		{"if (true) {10}", 10},
		{"if(false) {10}", nil},
		{"if (1) {10}", 10},
		{"if(1<2){10}", 10},
		{"if(1>2){10}", nil},
		{"if(1<2){10} else {20}", 10},
		{"if(1>2){10} else {20}", 20},
	}

	for _, tt := range tests {
		evaluated := testEval(tt.input)
		integer, ok := tt.expected.(int)
		if ok {
			testIntegerObject(t, evaluated, int64(integer))
		} else {
			testNullObject(t, evaluated)
		}
	}
}

func TestReturnStatements(t *testing.T) {
	tests := []struct {
		input    string
		expected int64
	}{
		{"return 10;", 10},
		{"return 10;9", 10},
		{"return 2*5;9;", 10},
		{"9;return 3 *5; 9;", 15},
		{
			`if ( 10 > 1) {
				if( 10 > 1) {
					return 10;
				}
				return 1;
				}
           `,
			10,
		},
	}
	for _, tt := range tests {
		evaluated := testEval(tt.input)
		testIntegerObject(t, evaluated, tt.expected)
	}
}

func TestErrorHandling(t *testing.T) {
	tests := []struct {
		input       string
		expectedMsg string
	}{
		{
			"5 + true",
			"type mismatch: INTEGER + BOOLEAN",
		},
		{
			"5 + true; 5;",
			"type mismatch: INTEGER + BOOLEAN",
		},
		{
			"-true",
			"unknown operator: -BOOLEAN",
		},
		{
			"true + false",
			"unknown operator: BOOLEAN + BOOLEAN",
		},
		{
			"5;true + false;5",
			"unknown operator: BOOLEAN + BOOLEAN",
		},
		{
			"if ( 10 > 1) { true + false; }",
			"unknown operator: BOOLEAN + BOOLEAN",
		},
		{
			`
			if (10 > 1) {
				if (10 > 1) {
					return true + false;
				}
				return 1;
			}
       		`,
			"unknown operator: BOOLEAN + BOOLEAN",
		},
		{
			"foobar",
			"identifier not found: foobar",
		},
	}

	for _, tt := range tests {
		evaluated := testEval(tt.input)

		errObj, ok := evaluated.(*object.Error)
		if !ok {
			t.Errorf("no error object returned. got=%T (%+v)", evaluated, evaluated)
			continue
		}
		if errObj.Msg != tt.expectedMsg {
			t.Errorf("wrong error message. expected=%q, got=%q", tt.expectedMsg, errObj.Msg)
		}
	}
}

func TestLetStatement(t *testing.T) {
	tests := []struct {
		input    string
		expected int64
	}{
		{"let a = 5;a;", 5},
		{"let a = 5 * 5;a;", 25},
		{"let a = 5;let b = a;b;", 5},
		{"let a = 5; let b = a;let c = a + b + 5;c;", 15},
	}

	for _, tt := range tests {
		testIntegerObject(t, testEval(tt.input), tt.expected)
	}
}

func TestFunctionObject(t *testing.T) {
	input := "fn(x) {x + 2;};"

	evaluated := testEval(input)
	fn, ok := evaluated.(*object.Function)
	if !ok {
		t.Fatalf("object is not Function. got=%T (%+v)", evaluated, evaluated)
	}

	if len(fn.Parameters) != 1 {
		t.Fatalf("function has wrong parameters. Parameters=%+v", fn.Parameters)
	}
	if fn.Parameters[0].String() != "x" {
		t.Fatalf("parameter is not 'x'. got=%q", fn.Parameters[0])
	}

	expectedBody := "(x + 2)"
	if fn.Body.String() != expectedBody {
		t.Fatalf("body is not %q. got=%q", expectedBody, fn.Body.String())
	}
}

func TestFunctionApplication(t *testing.T) {
	tests := []struct {
		input    string
		expected int64
	}{
		{"let identity = fn(x) {x;};identity(5);", 5},
		{"let identify = fn(x){return x;};identify(5);", 5},
		{"let double = fn(x) { x * 2; };double(5);", 10},
		{"let add = fn(x,y){x+y;};add(5,5);", 10},
		{"let add = fn(x,y){x+y;};add(5+5,add(5,5));", 20},
		{"fn(x){x;}(5)", 5},
	}

	for _, tt := range tests {
		testIntegerObject(t, testEval(tt.input), tt.expected)
	}
}

// --------------------------------------------------------------------------------------------------------------------

func testNullObject(t *testing.T, obj object.Object) bool {
	if obj != NULL {
		t.Errorf("object is not NULL. got=%T (%+v)", obj, obj)
		return false
	}
	return true
}

func testIntegerObject(t *testing.T, obj object.Object, expected int64) bool {
	result, ok := obj.(*object.Integer)
	if !ok {
		t.Errorf("object is not Integer. got=%T (%+v)", obj, obj)
		return false
	}
	if result.Value != expected {
		t.Errorf("object has wrong value. got=%d, want=%d", result.Value, expected)
		return false
	}
	return true
}
func testBooleanObject(t *testing.T, obj object.Object, expected bool) bool {
	result, ok := obj.(*object.Boolean)
	if !ok {
		t.Errorf("object is not Boolean. got=%T (%+v)", obj, obj)
		return false
	}
	if result.Value != expected {
		t.Errorf("object has wrong value. got=%t, want=%t", result.Value, expected)
		return false
	}
	return true
}
func testEval(input string) object.Object {
	l := lexer.New(input)
	p := parser.New(l)
	program := p.ParseProgram()
	env := object.NewEnvironment()

	return Eval(program, env)
}

func TestClosures(t *testing.T) {
	input := `
		let newAdder = fn(x) {
			fn (y) { x + y };
		};
		let addTwo = newAdder(2); addTwo(2);
     `

	testIntegerObject(t, testEval(input), 4)
}