diff --git a/src/main/java/SetCollection.java b/src/main/java/SetCollection.java
new file mode 100644
index 0000000..9cd1027
--- /dev/null
+++ b/src/main/java/SetCollection.java
@@ -0,0 +1,8 @@
+import java.util.Set;
+
+public class SetCollection {
+    public Integer getNumbersSize(Set<Integer> numbers) {
+        return numbers.size();
+    }
+
+}
diff --git a/src/main/java/StringPs.java b/src/main/java/StringPs.java
new file mode 100644
index 0000000..53b1e89
--- /dev/null
+++ b/src/main/java/StringPs.java
@@ -0,0 +1,15 @@
+public class StringPs {
+
+    public String[] stringSplit(String s) {
+        String[] arr = s.split(",");
+        return arr;
+    }
+
+    public String stringSub(String s) {
+        return s.substring(1,4);
+    }
+
+    public String stringCharAt(int i, String abc) {
+        return Character.toString(abc.charAt(i));
+    }
+}
diff --git a/src/test/java/SetCollectionTest.java b/src/test/java/SetCollectionTest.java
new file mode 100644
index 0000000..8a3c267
--- /dev/null
+++ b/src/test/java/SetCollectionTest.java
@@ -0,0 +1,58 @@
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class SetCollectionTest {
+    private Set<Integer> numbers;
+
+    @BeforeEach
+    void setUp() {
+        numbers = new HashSet<>();
+        numbers.add(1);
+        numbers.add(1);
+        numbers.add(2);
+        numbers.add(3);
+    }
+
+    @DisplayName("Hash 사이즈 검사 테스트")
+    @Test
+    public void testCheckSizeTest() {
+        SetCollection checkSize = new SetCollection();
+        Integer result = checkSize.getNumbersSize(this.numbers);
+        assertEquals(3, result);
+    }
+
+    @DisplayName("Hash안에 포함되어있는지 검사 테스트")
+    @Test
+    public void contains() {
+        assertThat(numbers.contains(1)).isTrue();
+        assertThat(numbers.contains(2)).isTrue();
+        assertThat(numbers.contains(3)).isTrue();
+    }
+
+    @DisplayName("중복된 메소드 제거 테스")
+    @ParameterizedTest
+    @ValueSource(ints= {1, 2, 3})
+    public void testContaionsTrueTes트t(int number) {
+        assertTrue(numbers.contains(number));
+    }
+
+    @DisplayName("포함된 값이 없으면 false 반환하는 테스트")
+    @ParameterizedTest
+    @CsvSource(value= {"1:true", "2:true", "3:true", "4:false", "5:false"}, delimiter = ':')
+    public void testContaionsTest(int input,boolean expected) {
+        boolean result = numbers.contains(input);
+        assertEquals(expected, result);
+    }
+    }
\ No newline at end of file
diff --git a/src/test/java/StringTest.java b/src/test/java/StringTest.java
new file mode 100644
index 0000000..45907c5
--- /dev/null
+++ b/src/test/java/StringTest.java
@@ -0,0 +1,44 @@
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+
+import static org.assertj.core.api.Assertions.*;
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class StringTest {
+
+    @DisplayName("배열의 숫자값들을트 ,을 기준으로 분리하는 테스트")
+    @Test
+    public void testSplitStringTest() {
+        String[] arr = {"1","2"};
+        StringPs splitString = new StringPs();
+        String[] result1 = splitString.stringSplit("1,2");
+        assertArrayEquals(arr,result1);
+        String[] arr2 = {"1"};
+        String[] result2 = splitString.stringSplit("1");
+        assertArrayEquals(arr2,result2);
+    }
+
+    @DisplayName("()를 제거하는 테스트")
+    @Test
+    public void testSubStringTest() {
+        String str = "1,2";
+        StringPs removeString = new StringPs();
+        String result = removeString.stringSub("(1,2)");
+        assertEquals(str, result);
+    }
+
+    @DisplayName("문자를 가져올때 위치값을 벗어나면 메세지가 발생하는 부분에 대한 테스트")
+    @Test
+    public void testCharAtStringTest() {
+        String str = "b";
+        StringPs charAtString = new StringPs();
+        String result = charAtString.stringCharAt(1,"abc");
+        assertEquals(str,result);
+        assertThatThrownBy(() -> {
+            charAtString.stringCharAt(50,"abc");
+        }).isInstanceOf(IndexOutOfBoundsException.class).hasMessageContaining("String index out of range:");
+    }
+    
+}