env_test.go

// Copyright 2012 Yuichi Araki. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package yall

import (
	"strconv"
	"testing"
)

type evalTestCase struct {
	input  string
	output string
}

var evalTestCases = []evalTestCase{
	evalTestCase{"()", "()"},
	evalTestCase{"123", "123"},
	evalTestCase{"(+ 1 2)", "3"},
	evalTestCase{"(+ 1 (* 2 3))", "7"},
	evalTestCase{"(cons 1 '(2))", "(1 2)"},
}

func TestEval(t *testing.T) {
	for _, tc := range evalTestCases {
		env := NewEnv()
		expr := env.EvalString(tc.input)
		if tc.output != expr.String() {
			t.Errorf("Received [[%v]] when expecting [[%v]]", expr.String(), tc.output)
		}
	}
}

// Interned symbol
func TestEval2(t *testing.T) {
	i := -10
	env := NewEnv()
	env.internVariable("a", NewInteger(i))
	expr := env.EvalString("a")
	if expr.String() != strconv.Itoa(i) {
		t.Errorf("Received [[%v]] when expecting [[%v]]", expr.String(), i)
	}
}

// Quasiquote
func TestEval3(t *testing.T) {
	env := NewEnv()
	env.internVariable("b", NewInteger(3))
	env.internVariable("c", NewCell(NewInteger(1), NewCell(NewInteger(2), Empty)))
	expr := env.EvalString("`(a ,b ,@c)")
	answer := "(a 3 1 2)"
	if expr.String() != answer {
		t.Errorf("Received [[%v]] when expecting [[%v]]", expr.String(), answer)
	}
}

// Closure (environment enclosing)
func TestEval4(t *testing.T) {
	env := NewEnv()
	env.EvalString("(def genc (lambda () ((lambda (x) (lambda () (inc! x))) 0)))")
	env.EvalString("(def a (genc))")
	if "1" != env.EvalString("(a)").String() {
		t.Errorf("Something is wrong with closure.")
	}
	if "2" != env.EvalString("(a)").String() {
		t.Errorf("Something is wrong with closure.")
	}
	if "3" != env.EvalString("(a)").String() {
		t.Errorf("Something is wrong with closure.")
	}
}