waiig15/parser/parser_prefix_test.go

package parser

import (
	"fmt"
	"testing"

	"code.osinet.fr/fgm/waiig15/ast"
	"code.osinet.fr/fgm/waiig15/lexer"
)

func testIntegerLiteral(t *testing.T, il ast.Expression, value int64) bool {
	integ, ok := il.(*ast.IntegerLiteral)
	if !ok {
		t.Errorf("il not *ast.IntegerLiteral. got=%T", il)
		return false
	}

	if integ.Value != value {
		t.Errorf("integ.Value not %d. got =%d", value, integ.Value)
		return false
	}

	if integ.TokenLiteral() != fmt.Sprintf("%d", value) {
		t.Errorf("integ.TokenLiteral not %d. got=%s",
			value, integ.TokenLiteral())
		return false
	}

	return true
}

func TestParsingPrefixExpressions(t *testing.T) {
	prefixTests := []struct {
		input        string
		operator     string
		integerValue int64
	}{
		{"!5", "!", 5},
		{"-15", "-", 15},
	}

	for _, tt := range prefixTests {
		l := lexer.New(tt.input)
		p := New(l)
		program := p.ParseProgram()
		checkParserErrors(t, p)

		if len(program.Statements) != 1 {
			t.Fatalf("program.Statements does not contain %d statements, got=%d\n",
				1, len(program.Statements))
		}

		stmt, ok := program.Statements[0].(*ast.ExpressionStatement)
		if !ok {
			t.Fatalf("program.STatements[0] is not ast.ExpressionStatement. got=%T",
				program.Statements[0])
		}

		exp, ok := stmt.Expression.(*ast.PrefixExpression)
		if !ok {
			t.Fatalf("stms is not ast.PrefixExpression. got=%T",
				stmt.Expression)
		}

		if exp.Operator != tt.operator {
			t.Fatalf("exp.Operator is not '%s'. got=%s",
				tt.operator, exp.Operator)
		}

		if !testIntegerLiteral(t, exp.Right, tt.integerValue) {
			return
		}
	}
}