diff --git a/lexer/lexer_test.go b/lexer/lexer_test.go
index 27216d0..d67e691 100644
--- a/lexer/lexer_test.go
+++ b/lexer/lexer_test.go
@@ -3,8 +3,10 @@ package lexer
 import "testing"
 import "git.tebibyte.media/sashakoshka/arf/file"
 import "git.tebibyte.media/sashakoshka/arf/types"
+import "git.tebibyte.media/sashakoshka/arf/infoerr"
 
 func checkTokenSlice (filePath string, correct []Token, test *testing.T) {
+	test.Log("checking lexer results for", filePath)
 	file, err := file.Open(filePath)
 	if err != nil {
 		test.Log(err)
@@ -46,6 +48,62 @@ func checkTokenSlice (filePath string, correct []Token, test *testing.T) {
 	test.Log("token slice content match")
 }
 
+func compareErr (
+	filePath string,
+	correctKind    infoerr.ErrorKind,
+	correctMessage string,
+	correctRow     int,
+	correctColumn  int,
+	correctWidth   int,
+	test *testing.T,
+) {
+	test.Log("testing errors in", filePath)
+	file, err := file.Open(filePath)
+	if err != nil {
+		test.Log(err)
+		test.Fail()
+		return
+	}
+	
+	_, err = Tokenize(file)
+	check := err.(infoerr.Error)
+
+	if check.Kind() != correctKind {
+		test.Log("mismatched error kind")
+		test.Log("- want:", correctKind)
+		test.Log("- have:", check.Kind())
+		test.Fail()
+	}
+
+	if check.Message() != correctMessage {
+		test.Log("mismatched error message")
+		test.Log("- want:", correctMessage)
+		test.Log("- have:", check.Message())
+		test.Fail()
+	}
+
+	if check.Row() != correctRow {
+		test.Log("mismatched error row")
+		test.Log("- want:", correctRow)
+		test.Log("- have:", check.Row())
+		test.Fail()
+	}
+
+	if check.Column() != correctColumn {
+		test.Log("mismatched error column")
+		test.Log("- want:", correctColumn)
+		test.Log("- have:", check.Column())
+		test.Fail()
+	}
+
+	if check.Width() != correctWidth {
+		test.Log("mismatched error width")
+		test.Log("- want:", check.Width())
+		test.Log("- have:", correctWidth)
+		test.Fail()
+	}
+}
+
 func TestTokenizeAll (test *testing.T) {
 	checkTokenSlice("../tests/lexer/all.arf", []Token {
 		Token { kind: TokenKindSeparator },
@@ -161,3 +219,12 @@ func TestTokenizeIndent (test *testing.T) {
 		Token { kind: TokenKindNewline },
 	}, test)
 }
+
+func TestTokenizeErr (test *testing.T) {
+	compareErr (
+		"../tests/lexer/error.arf",
+		infoerr.ErrorKindError,
+		"unexpected symbol character ;",
+		1, 0, 1,
+		test)
+}
diff --git a/tests/lexer/error.arf b/tests/lexer/error.arf
new file mode 100644
index 0000000..9957cde
--- /dev/null
+++ b/tests/lexer/error.arf
@@ -0,0 +1,2 @@
+:arf
+;