diff --git a/test/test_StringManipulation.c b/test/test_StringManipulation.c
index 7da5755..6e0e9eb 100644
--- a/test/test_StringManipulation.c
+++ b/test/test_StringManipulation.c
@@ -4,10 +4,20 @@
 #include <unity.h>
 #include "../src/stringManipulation.c"
 
+void test_everyCharacterIsDigit()
+{
+	/*test values*/
+	char str_1[] = "1234", str_2[] = "hey123", str_3[] = "good evening!", str_4[] = "äöü";
+	
+	/*assertions*/
+	TEST_ASSERT_TRUE(everyCharacterIsDigit(str_1));
+	TEST_ASSERT_FALSE(everyCharacterIsDigit(str_2));
+	TEST_ASSERT_FALSE(everyCharacterIsDigit(str_3));
+	TEST_ASSERT_FALSE(everyCharacterIsDigit(str_4));
+}
 
 void test_power()
 {
-	
 	/*test block 1*/
 	int testValues[] = {1,2,3,4,5,6,7,8,9,10};
 	int expectedValues[] = {1,4,9,16,25,36,49,64,81,100};