add bit string to int array conversion

src/test/java/ch/fhnw/kry/SPNTest.java

@@ -73,4 +73,16 @@ class SPNTest {
         assertEquals(y, spn.encryptBlock(key, x));
         assertEquals(x, spn.decryptBlock(key, y));
     }
+
+    @Test
+    void strToArray() {
+        var spn = new SPN();
+
+        String input = "00000100110100100000101110111000000000101000111110001110011111110110000001010001010000111010000000010011011001110010101110110000";
+        int[] data = spn.strToArray(input);
+
+        assertEquals(8, data.length);
+        assertEquals(0x04D2, data[0]);
+        assertEquals(0x2BB0, data[data.length - 1]);
+    }
 }