From f141d2d07f0c1da27cc044cae11583413bfa5808 Mon Sep 17 00:00:00 2001
From: Emmanuel Di Pretoro <edipretoro@gmail.com>
Date: Wed, 18 Mar 2026 21:59:49 +0100
Subject: [PATCH] Adding tests about the lexer

---
 lexer/lexer_test.go | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 lexer/lexer_test.go

diff --git a/lexer/lexer_test.go b/lexer/lexer_test.go
new file mode 100644
index 0000000..81dd6d6
--- /dev/null
+++ b/lexer/lexer_test.go
@@ -0,0 +1,42 @@
+package lexer
+
+import (
+	"testing"
+
+	"github.com/edipretoro/waiig_monkey/token"
+)
+
+func TestNextToken(t *testing.T) {
+	input := "=+(){},;"
+
+	tests := []struct {
+		expectedType    token.TokenType
+		expectedLiteral string
+	}{
+		{token.ASSIGN, "="},
+		{token.PLUS, "+"},
+		{token.LPAREN, "("},
+		{token.RPAREN, ")"},
+		{token.LBRACE, "{"},
+		{token.RBRACE, "}"},
+		{token.COMMA, ","},
+		{token.SEMICOLON, ";"},
+		{token.EOF, ""},
+	}
+
+	l := New(input)
+	for i, tt := range tests {
+		tok := l.NextToken()
+
+		if tok.Type != tt.expectedType {
+			t.Fatal("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)
+		}
+
+	}
+}