Added test for capitalize and trimToNull

Signed-off-by: Arnau Mora <[email protected]>

lib/src/test/java/at/bitfire/vcard4android/UtilsTest.kt

@@ -0,0 +1,25 @@
+package at.bitfire.vcard4android
+
+import at.bitfire.vcard4android.Utils.capitalize
+import at.bitfire.vcard4android.Utils.trimToNull
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Test
+
+class UtilsTest {
+    @Test
+    fun testCapitalize() {
+        assertEquals("Utils Test", "utils test".capitalize()) // Test multiple words
+        assertEquals("Utils", "utils".capitalize()) // Test single word
+        assertEquals("", "".capitalize()) // Test empty string
+    }
+
+    @Test
+    fun testTrimToNull() {
+        assertEquals("test", "  test".trimToNull()) // Test spaces only before
+        assertEquals("test", "test  ".trimToNull()) // Test spaces only after
+        assertEquals("test", "  test  ".trimToNull()) // Test spaces before and after
+        assertNull("     ".trimToNull()) // Test spaces
+        assertNull("".trimToNull()) // Test empty string
+    }
+}