diff --git a/test/com/ctci/arraysandstrings/StringCompressionTest.java b/test/com/ctci/arraysandstrings/StringCompressionTest.java
new file mode 100644
index 00000000..035aa2f6
--- /dev/null
+++ b/test/com/ctci/arraysandstrings/StringCompressionTest.java
@@ -0,0 +1,26 @@
+package com.ctci.arraysandstrings;
+
+import org.junit.Before;
+import org.junit.Test;
+
+public class StringCompressionTest {
+	public static String str1;
+
+	public static String str2;
+
+	public static String str3;
+
+	@Before
+	public void setup() {
+		str1 = "aaabbccaaaaa";
+		str2 = "adddcc2";
+		str3 = "";
+	}
+
+	@Test
+	public void testCompressStr() {
+		System.out.println(str1 + ": " + StringCompression.compressString(str1));
+		System.out.println(str2 + ": " + StringCompression.compressString(str2));
+		System.out.println(str3 + ": " + StringCompression.compressString(str3));
+	}
+}
\ No newline at end of file
diff --git a/test/com/ctci/stacksandqueues/SortStackTest.java b/test/com/ctci/stacksandqueues/SortStackTest.java
new file mode 100644
index 00000000..18004816
--- /dev/null
+++ b/test/com/ctci/stacksandqueues/SortStackTest.java
@@ -0,0 +1,46 @@
+package com.ctci.stacksandqueues;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.util.Stack;
+
+import org.junit.jupiter.api.Test;
+
+class SortStackTest {
+
+	@Test
+	void testCase1() {
+		Stack<Integer> unsortedStack = new Stack<>();
+		unsortedStack.push(2);
+		unsortedStack.push(5);
+		unsortedStack.push(1);
+		unsortedStack.push(3);
+		SortStack.sortStack(unsortedStack);		
+		assertEquals(1,unsortedStack.pop());
+		assertEquals(2,unsortedStack.pop());
+		assertEquals(3,unsortedStack.pop());	
+		assertEquals(5,unsortedStack.pop());
+	}
+	
+	@Test
+	void testCase2() {
+		Stack<Integer> unsortedStack = new Stack<>();
+		SortStack.sortStack(unsortedStack);		
+		assertTrue(unsortedStack.isEmpty());
+	}	
+	
+	@Test
+	void testCase3() {
+		Stack<Integer> unsortedStack = new Stack<>();
+		unsortedStack.push(5);
+		unsortedStack.push(3);
+		unsortedStack.push(2);		
+		unsortedStack.push(1);		
+		SortStack.sortStack(unsortedStack);		
+		assertEquals(1,unsortedStack.pop());
+		assertEquals(2,unsortedStack.pop());
+		assertEquals(3,unsortedStack.pop());
+		assertEquals(5,unsortedStack.pop());
+	}
+
+}