waiig15/lexer/lexer_test.go

package lexer

import (
	"fgm/waiig15/token"
	"testing"
)

func TestNextToken(t *testing.T) {
	input := `
let five = 5;
let ten  = 10;

let add = fn(x, y) {
  x + y;
}

let result = add(five, ten);
`

	tests := []struct {
		expectedType    token.TokenType
		expectedLiteral string
	}{
		{ token.LET, "let" },
		{ token.IDENT, "five" },
		{ token.ASSIGN, "="},
		{ token.INT, "5" },
		{ token.SEMICOLON, ";" },

		{ token.LET, "let" },
		{ token.IDENT, "ten" },
		{ token.ASSIGN, "="},
		{ token.INT, "10" },
		{ token.SEMICOLON, ";" },

		{ token.LET, "let" },
		{ token.IDENT, "add" },
		{ token.ASSIGN, "="},
		{ token.FUNCTION, "fn" },
		{ token.LPAREN, "(" },
		{ token.IDENT, "x" },
		{ token.COMMA, "," },
		{ token.IDENT, "y" },
		{ token.RPAREN, ")" },
		{ token.LBRACE, "{" },
		{ token.IDENT, "x" },
		{ token.PLUS, "+" },
		{ token.IDENT, "y" },
		{ token.SEMICOLON, ";" },
		{ token.RBRACE, "}" },

		{ token.LET, "let" },
		{ token.IDENT, "result" },
		{ token.ASSIGN, "="},
		{ token.IDENT, "add" },
		{ token.LPAREN, "(" },
		{ token.IDENT, "five" },
		{ token.COMMA, "," },
		{ token.IDENT, "ten" },
		{ token.RPAREN, ")" },
		{token.SEMICOLON, ";"},
		{token.EOF, ""},
	}

	l := New(input)

	for i, tt := range tests {
		tok := l.NextToken()

		if tok.Type != tt.expectedType {
			t.Fatalf("tests[%d] - tokentype wrong, expected %q, got %q",
				i, tt.expectedType, tok.Type)
		}

		if tok.Literal != tt.expectedLiteral {
			t.Fatalf("tests[%d] - literal wrong, expected %q, got %q",
				i, tt.expectedLiteral, tok.Literal)
		}
	}
}