diff --git a/parser/parser_test.go b/parser/parser_test.go
index f869eb5..6c7df26 100644
--- a/parser/parser_test.go
+++ b/parser/parser_test.go
@@ -92,18 +92,7 @@ func TestIdentifierExpression(t *testing.T) {
 		t.Fatalf("program.Statements[0] is not ast.ExpressionStatement. got=%T", program.Statements[0])
 	}
 
-	ident, ok := stmt.Expression.(*ast.Identifier)
-	if !ok {
-		t.Fatalf("exp not *ast.Identifier. got=%T", stmt.Expression)
-	}
-
-	if ident.Value != "foobar" {
-		t.Errorf("ident.Value not %s. got=%s", "foobar", ident.Value)
-	}
-
-	if ident.TokenLiteral() != "foobar" {
-		t.Errorf("ident.TokenLiteral() not %s. got=%s", "foobar", ident.TokenLiteral())
-	}
+	testLiteralExpression(t, stmt.Expression, "foobar")
 }
 
 func TestIntegerLiteralExpression(t *testing.T) {
@@ -123,16 +112,7 @@ func TestIntegerLiteralExpression(t *testing.T) {
 		t.Fatalf("program.Statements[0] is not ast.ExpressionStatement. got=%T", program.Statements[0])
 	}
 
-	literal, ok := stmt.Expression.(*ast.IntegerLiteral)
-	if !ok {
-		t.Fatalf("exp is not *ast.IntegerLiteral. got=%T", stmt.Expression)
-	}
-	if literal.Value != 5 {
-		t.Errorf("literal.Value not %d. got=%d", 5, literal.Value)
-	}
-	if literal.TokenLiteral() != "5" {
-		t.Errorf("literal.TokenLiteral not %s. got=%s", "5", literal.TokenLiteral())
-	}
+	testLiteralExpression(t, stmt.Expression, 5)
 }
 
 func TestParsingPrefixExpressions(t *testing.T) {
@@ -207,22 +187,7 @@ func TestParsingInfixExpressions(t *testing.T) {
 			t.Fatalf("program.Statements[0] is not ast.ExpressionStatement. got=%T\n", program.Statements[0])
 		}
 
-		exp, ok := stmt.Expression.(*ast.InfixExpression)
-		if !ok {
-			t.Fatalf("stmt is not ast.InfixExpression. got=%T", stmt.Expression)
-		}
-
-		if !testIntegerLiteral(t, exp.Left, tt.leftValue) {
-			return
-		}
-
-		if exp.Operator != tt.operator {
-			t.Fatalf("exp.Operator is not '%s'. got=%s", tt.operator, exp.Operator)
-		}
-
-		if !testIntegerLiteral(t, exp.Right, tt.rightValue) {
-			return
-		}
+		testInfixExpression(t, stmt.Expression, tt.leftValue, tt.operator, tt.rightValue)
 	}
 }
 
@@ -339,6 +304,63 @@ func testIntegerLiteral(t *testing.T, il ast.Expression, value int64) bool {
 	return true
 }
 
+func testIdentifier(t *testing.T, exp ast.Expression, value string) bool {
+	ident, ok := exp.(*ast.Identifier)
+	if !ok {
+		t.Errorf("exp not *ast.Identifier. got=%T", exp)
+		return false
+	}
+
+	if ident.Value != value {
+		t.Errorf("ident.Value not %s. got=%s", value, ident.Value)
+		return false
+	}
+
+	if ident.TokenLiteral() != value {
+		t.Errorf("ident.TokenLiteral() not %s. got=%s", value, ident.TokenLiteral())
+		return false
+	}
+
+	return true
+}
+
+func testLiteralExpression(t *testing.T, exp ast.Expression, expected interface{}) bool {
+	switch v := expected.(type) {
+	case int:
+		return testIntegerLiteral(t, exp, int64(v))
+	case int64:
+		return testIntegerLiteral(t, exp, v)
+	case string:
+		return testIdentifier(t, exp, v)
+	}
+
+	t.Errorf("type of exp not handled. got=%T", expected)
+	return false
+}
+
+func testInfixExpression(t *testing.T, exp ast.Expression, left interface{}, operator string, right interface{}) bool {
+	opExp, ok := exp.(*ast.InfixExpression)
+	if !ok {
+		t.Errorf("exp is not ast.InfixExpression. got=%T(%s)", exp, exp)
+		return false
+	}
+
+	if !testLiteralExpression(t, opExp.Left, left) {
+		return false
+	}
+
+	if opExp.Operator != operator {
+		t.Errorf("exp.Operator is not '%s'. got=%q", operator, opExp.Operator)
+		return false
+	}
+
+	if !testLiteralExpression(t, opExp.Right, right) {
+		return false
+	}
+
+	return true
+}
+
 func checkParserErrors(t *testing.T, p *Parser) {
 	errors := p.Errors()
 	if len(errors) == 0 {