diff --git a/func_test.go b/func_test.go
deleted file mode 100644
index aafcea4..0000000
--- a/func_test.go
+++ /dev/null
@@ -1,56 +0,0 @@
-package xpath
-
-import "testing"
-
-type testQuery string
-
-func (t testQuery) Select(_ iterator) NodeNavigator {
-	panic("implement me")
-}
-
-func (t testQuery) Clone() query {
-	return t
-}
-
-func (t testQuery) Evaluate(_ iterator) interface{} {
-	return string(t)
-}
-
-func (t testQuery) ValueType() resultType {
-	return xpathResultType.Any
-}
-
-func (t testQuery) Properties() queryProp {
-	return queryProps.None
-}
-
-const strForNormalization = "\t    \rloooooooonnnnnnngggggggg  \r \n tes  \u00a0 t strin \n\n \r g "
-const expectedStrAfterNormalization = `loooooooonnnnnnngggggggg tes t strin g`
-
-func Test_NormalizeSpaceFunc(t *testing.T) {
-	result := normalizespaceFunc(testQuery(strForNormalization), nil).(string)
-	if expectedStrAfterNormalization != result {
-		t.Fatalf("unexpected result '%s'", result)
-	}
-}
-
-func Test_ConcatFunc(t *testing.T) {
-	result := concatFunc(testQuery("a"), testQuery("b"))(nil, nil).(string)
-	if "ab" != result {
-		t.Fatalf("unexpected result '%s'", result)
-	}
-}
-
-func Benchmark_NormalizeSpaceFunc(b *testing.B) {
-	b.ReportAllocs()
-	for i := 0; i < b.N; i++ {
-		_ = normalizespaceFunc(testQuery(strForNormalization), nil)
-	}
-}
-
-func Benchmark_ConcatFunc(b *testing.B) {
-	b.ReportAllocs()
-	for i := 0; i < b.N; i++ {
-		_ = concatFunc(testQuery("a"), testQuery("b"))(nil, nil)
-	}
-}
diff --git a/xpath_function_test.go b/xpath_function_test.go
index f446c44..aed0824 100644
--- a/xpath_function_test.go
+++ b/xpath_function_test.go
@@ -43,6 +43,8 @@ func Test_func_concat(t *testing.T) {
 	test_xpath_eval(t, empty_example, `concat("1", "2", "3")`, "123")
 	//test_xpath_eval(t, empty_example, `concat("Ciao!", ())`, "Ciao!")
 	test_xpath_eval(t, book_example, `concat(//book[1]/title, ", ", //book[1]/year)`, "Everyday Italian, 2005")
+	result := concatFunc(testQuery("a"), testQuery("b"))(nil, nil).(string)
+	assertEqual(t, result, "ab")
 }
 
 func Test_func_contains(t *testing.T) {
@@ -220,7 +222,26 @@ func Test_func_namespace_uri(t *testing.T) {
 }
 
 func Test_func_normalize_space(t *testing.T) {
+	const testStr = "\t    \rloooooooonnnnnnngggggggg  \r \n tes  \u00a0 t strin \n\n \r g "
+	const expectedStr = `loooooooonnnnnnngggggggg tes t strin g`
+	test_xpath_eval(t, employee_example, `normalize-space("`+testStr+`")`, expectedStr)
+
 	test_xpath_eval(t, empty_example, `normalize-space(' abc ')`, "abc")
 	test_xpath_eval(t, book_example, `normalize-space(//book/title)`, "Everyday Italian")
 	test_xpath_eval(t, book_example, `normalize-space(//book[1]/title)`, "Everyday Italian")
 }
+
+func Benchmark_NormalizeSpaceFunc(b *testing.B) {
+	b.ReportAllocs()
+	const strForNormalization = "\t    \rloooooooonnnnnnngggggggg  \r \n tes  \u00a0 t strin \n\n \r g "
+	for i := 0; i < b.N; i++ {
+		_ = normalizespaceFunc(testQuery(strForNormalization), nil)
+	}
+}
+
+func Benchmark_ConcatFunc(b *testing.B) {
+	b.ReportAllocs()
+	for i := 0; i < b.N; i++ {
+		_ = concatFunc(testQuery("a"), testQuery("b"))(nil, nil)
+	}
+}
diff --git a/xpath_test.go b/xpath_test.go
index f89fa42..99b2873 100644
--- a/xpath_test.go
+++ b/xpath_test.go
@@ -15,6 +15,28 @@ var (
 	mybook_example   = createMyBookExample()
 )
 
+type testQuery string
+
+func (t testQuery) Select(_ iterator) NodeNavigator {
+	panic("implement me")
+}
+
+func (t testQuery) Clone() query {
+	return t
+}
+
+func (t testQuery) Evaluate(_ iterator) interface{} {
+	return string(t)
+}
+
+func (t testQuery) ValueType() resultType {
+	return xpathResultType.Any
+}
+
+func (t testQuery) Properties() queryProp {
+	return queryProps.None
+}
+
 func test_xpath_elements(t *testing.T, root *TNode, expr string, expected ...int) {
 	result := selectNodes(root, expr)
 	assertEqual(t, len(expected), len(result))