diff --git a/src/main/java/ua/net/uid/utils/helpers/CommonHelper.java b/src/main/java/ua/net/uid/utils/helpers/CommonHelper.java
index 9c7af9f..8a5f816 100644
--- a/src/main/java/ua/net/uid/utils/helpers/CommonHelper.java
+++ b/src/main/java/ua/net/uid/utils/helpers/CommonHelper.java
@@ -109,7 +109,7 @@
         T result = null;
         if (!isEmpty(items)) {
             for (T item : items)
-                if (comparator.compare(result, item) < 0)
+                if (comparator.compare(result, item) > 0)
                     result = item;
         }
         return result;
@@ -120,7 +120,7 @@
         T result = null;
         if (!isEmpty(items)) {
             for (T item : items)
-                if (comparator.compare(result, item) > 0)
+                if (comparator.compare(result, item) < 0)
                     result = item;
         }
         return result;
diff --git a/src/test/java/ua/net/uid/utils/helpers/CommonHelperTest.java b/src/test/java/ua/net/uid/utils/helpers/CommonHelperTest.java
index 44db5fd..f162761 100644
--- a/src/test/java/ua/net/uid/utils/helpers/CommonHelperTest.java
+++ b/src/test/java/ua/net/uid/utils/helpers/CommonHelperTest.java
@@ -4,11 +4,18 @@
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
+import java.util.Collections;
+import java.util.Comparator;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Map;
+import java.util.Set;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 class CommonHelperTest {
@@ -73,12 +80,91 @@
         assertFalse(CommonHelper.isEmpty(src));
     }
 
+    @Test
+    void testIsEmptyObject() {
+        assertTrue(CommonHelper.isEmpty((Object) null));
+        assertTrue(CommonHelper.isEmpty((Object) ""));
+        assertFalse(CommonHelper.isEmpty((Object) "0"));
+        assertTrue(CommonHelper.isEmpty((Object) new byte[] {}));
+        assertFalse(CommonHelper.isEmpty((Object) new int[] {1,2,3}));
+        assertTrue(CommonHelper.isEmpty((Object) Arrays.asList()));
+        assertFalse(CommonHelper.isEmpty((Object) Arrays.asList(1,2,3)));
+        assertTrue(CommonHelper.isEmpty((Object) Collections.emptyMap()));
+        Map<String, Integer> map = new HashMap<>();
+        assertTrue(CommonHelper.isEmpty((Object) map));
+        map.put("q", 1);
+        assertFalse(CommonHelper.isEmpty((Object) map));
+    }
+
+    @Test
+    void testCoalesce() {
+        assertNull(CommonHelper.coalesce());
+        assertNull(CommonHelper.coalesce(null, null));
+        assertEquals(1, CommonHelper.coalesce(1, null, null));
+        assertEquals(2, CommonHelper.coalesce(null, 2, null));
+        assertEquals(3, CommonHelper.coalesce(null, null, 3));
+        assertEquals(1, CommonHelper.coalesce(1, null, 3));
+    }
+
+    @Test
+    void testCompareNullable() {
+        assertTrue(CommonHelper.compare(null, null, true) == 0);
+        assertTrue(CommonHelper.compare(null, null, false) == 0);
+        assertTrue(CommonHelper.compare(null, 1, false) < 0);
+        assertTrue(CommonHelper.compare(null, 1, true) > 0);
+        assertTrue(CommonHelper.compare(1, null, false) > 0);
+        assertTrue(CommonHelper.compare(1, null, true) < 0);
+        assertTrue(CommonHelper.compare(1, 1, false) == 0);
+        assertTrue(CommonHelper.compare(1, 1, true) == 0);
+        assertTrue(CommonHelper.compare(-1, 1, false) < 0);
+        assertTrue(CommonHelper.compare(-1, 1, true) < 0);
+        assertTrue(CommonHelper.compare(1, -1, false) > 0);
+        assertTrue(CommonHelper.compare(1, -1, true) > 0);
+    }
+
+    @Test
+    void testMinComparable() {
+        assertNull(CommonHelper.min());
+        assertNull(CommonHelper.min((Integer) null));
+        assertEquals(0, CommonHelper.min(null, 3, 1, 0, 2, 4, null));
+    }
+
+    @Test
+    void testMaxComparable() {
+        assertNull(CommonHelper.max());
+        assertNull(CommonHelper.max((Integer) null));
+        assertEquals(4, CommonHelper.max(null, 3, 1, 0, 2, 4, null));
+    }
+
+    @Test
+    void testMinByComparator() {
+        Comparator<Integer> comparator = (a, b) -> CommonHelper.compare(a, b, true);
+        assertNull(CommonHelper.minBy(comparator));
+        assertNull(CommonHelper.minBy(comparator, (Integer) null));
+        assertEquals(0, CommonHelper.minBy(comparator, null, 3, 1, 0, 2, 4, null));
+    }
+
+    @Test
+    void testMaxByComparator() {
+        Comparator<Integer> comparator = (a, b) -> CommonHelper.compare(a, b, false);
+        assertNull(CommonHelper.maxBy(comparator));
+        assertNull(CommonHelper.maxBy(comparator, (Integer) null));
+        assertEquals(4, CommonHelper.maxBy(comparator, null, 3, 1, 0, 2, 4, null));
+    }
+
+    @Test
+    void testSetOf() {
+        Set<Integer> expected = new HashSet<>(Arrays.asList(3,1,5,7,3));
+        Set<Integer> actual = CommonHelper.setOf(3,1,1,5,7,3,5);
+        assertEquals(expected, actual);
+    }
+
     static class AutoCloseableImpl implements AutoCloseable {
         boolean called = false;
 
         @Override
         public void close() throws Exception {
-            called = true;
+            called = true; Map.of();
             throw new IOException("test exception");
         }
     }