From 89d1a7b0b9d007033111446388fa09af3586a324 Mon Sep 17 00:00:00 2001
From: alxkm <alexanderklmn@gmail.com>
Date: Sun, 20 Jul 2025 00:01:35 +0200
Subject: [PATCH 1/2] testing: improve CircularBufferTest

---
 .../buffers/CircularBufferTest.java           | 152 +++++++++++++++++-
 1 file changed, 148 insertions(+), 4 deletions(-)

diff --git a/src/test/java/com/thealgorithms/datastructures/buffers/CircularBufferTest.java b/src/test/java/com/thealgorithms/datastructures/buffers/CircularBufferTest.java
index b115fc187b1a..09adb07d9484 100644
--- a/src/test/java/com/thealgorithms/datastructures/buffers/CircularBufferTest.java
+++ b/src/test/java/com/thealgorithms/datastructures/buffers/CircularBufferTest.java
@@ -2,7 +2,6 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNull;
-import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import org.junit.jupiter.api.Test;
@@ -68,11 +67,11 @@ void testFullBuffer() {
 
     @Test
     void testIllegalArguments() {
-        assertThrows(IllegalArgumentException.class, () -> new CircularBuffer<>(0));
-        assertThrows(IllegalArgumentException.class, () -> new CircularBuffer<>(-1));
+        org.junit.jupiter.api.Assertions.assertThrows(IllegalArgumentException.class, () -> new CircularBuffer<>(0));
+        org.junit.jupiter.api.Assertions.assertThrows(IllegalArgumentException.class, () -> new CircularBuffer<>(-1));
 
         CircularBuffer<String> buffer = new CircularBuffer<>(1);
-        assertThrows(IllegalArgumentException.class, () -> buffer.put(null));
+        org.junit.jupiter.api.Assertions.assertThrows(IllegalArgumentException.class, () -> buffer.put(null));
     }
 
     @Test
@@ -85,4 +84,149 @@ void testLargeBuffer() {
         buffer.put(1000); // This should overwrite 0
         assertEquals(1, buffer.get());
     }
+
+    @Test
+    void testPutAfterGet() {
+        CircularBuffer<Integer> buffer = new CircularBuffer<>(2);
+        buffer.put(10);
+        buffer.put(20);
+        assertEquals(10, buffer.get());
+        buffer.put(30);
+        assertEquals(20, buffer.get());
+        assertEquals(30, buffer.get());
+        assertNull(buffer.get());
+    }
+
+    @Test
+    void testMultipleWrapArounds() {
+        CircularBuffer<Integer> buffer = new CircularBuffer<>(3);
+        for (int i = 1; i <= 6; i++) {
+            buffer.put(i);
+            buffer.get(); // add and immediately remove
+        }
+        assertTrue(buffer.isEmpty());
+        assertNull(buffer.get());
+    }
+
+    @Test
+    void testOverwriteMultipleTimes() {
+        CircularBuffer<String> buffer = new CircularBuffer<>(2);
+        buffer.put("X");
+        buffer.put("Y");
+        buffer.put("Z"); // overwrites "X"
+        buffer.put("W"); // overwrites "Y"
+        assertEquals("Z", buffer.get());
+        assertEquals("W", buffer.get());
+        assertNull(buffer.get());
+    }
+
+    @Test
+    void testIsEmptyAndIsFullTransitions() {
+        CircularBuffer<Integer> buffer = new CircularBuffer<>(2);
+        assertTrue(buffer.isEmpty());
+        org.junit.jupiter.api.Assertions.assertFalse(buffer.isFull());
+
+        buffer.put(1);
+        org.junit.jupiter.api.Assertions.assertFalse(buffer.isEmpty());
+        org.junit.jupiter.api.Assertions.assertFalse(buffer.isFull());
+
+        buffer.put(2);
+        assertTrue(buffer.isFull());
+
+        buffer.get();
+        org.junit.jupiter.api.Assertions.assertFalse(buffer.isFull());
+
+        buffer.get();
+        assertTrue(buffer.isEmpty());
+    }
+
+    @Test
+    void testInterleavedPutAndGet() {
+        CircularBuffer<String> buffer = new CircularBuffer<>(3);
+        buffer.put("A");
+        buffer.put("B");
+        assertEquals("A", buffer.get());
+        buffer.put("C");
+        assertEquals("B", buffer.get());
+        assertEquals("C", buffer.get());
+        assertNull(buffer.get());
+    }
+
+    @Test
+    void testRepeatedNullInsertionThrows() {
+        CircularBuffer<Object> buffer = new CircularBuffer<>(5);
+        for (int i = 0; i < 3; i++) {
+            int finalI = i;
+            org.junit.jupiter.api.Assertions.assertThrows(IllegalArgumentException.class, () -> buffer.put(null), "Iteration: " + finalI);
+        }
+    }
+    @Test
+    void testFillThenEmptyThenReuseBuffer() {
+        CircularBuffer<Integer> buffer = new CircularBuffer<>(3);
+
+        buffer.put(1);
+        buffer.put(2);
+        buffer.put(3);
+        assertTrue(buffer.isFull());
+
+        assertEquals(1, buffer.get());
+        assertEquals(2, buffer.get());
+        assertEquals(3, buffer.get());
+
+        assertTrue(buffer.isEmpty());
+
+        buffer.put(4);
+        buffer.put(5);
+        assertEquals(4, buffer.get());
+        assertEquals(5, buffer.get());
+        assertTrue(buffer.isEmpty());
+    }
+
+    @Test
+    void testPutReturnsTrueOnlyIfPreviouslyEmpty() {
+        CircularBuffer<String> buffer = new CircularBuffer<>(2);
+
+        assertTrue(buffer.put("one"));  // was empty
+        org.junit.jupiter.api.Assertions.assertFalse(buffer.put("two")); // not empty
+        org.junit.jupiter.api.Assertions.assertFalse(buffer.put("three")); // overwrite
+    }
+
+    @Test
+    void testOverwriteAndGetAllElementsCorrectly() {
+        CircularBuffer<Integer> buffer = new CircularBuffer<>(3);
+
+        buffer.put(1);
+        buffer.put(2);
+        buffer.put(3);
+        buffer.put(4); // Overwrites 1
+        buffer.put(5); // Overwrites 2
+
+        assertEquals(3, buffer.get());
+        assertEquals(4, buffer.get());
+        assertEquals(5, buffer.get());
+        assertNull(buffer.get());
+    }
+
+    @Test
+    void testBufferWithOneElementCapacity() {
+        CircularBuffer<String> buffer = new CircularBuffer<>(1);
+
+        assertTrue(buffer.put("first"));
+        assertEquals("first", buffer.get());
+        assertNull(buffer.get());
+
+        assertTrue(buffer.put("second"));
+        assertEquals("second", buffer.get());
+    }
+
+    @Test
+    void testPointerWraparoundWithExactMultipleOfCapacity() {
+        CircularBuffer<Integer> buffer = new CircularBuffer<>(3);
+        for (int i = 0; i < 6; i++) {
+            buffer.put(i);
+            buffer.get(); // keep buffer size at 0
+        }
+        assertTrue(buffer.isEmpty());
+        assertNull(buffer.get());
+    }
 }

From c001f41e3ff4b57b853746b65c06e4db24c75bed Mon Sep 17 00:00:00 2001
From: alxkm <alexanderklmn@gmail.com>
Date: Sun, 20 Jul 2025 00:04:07 +0200
Subject: [PATCH 2/2] style: redundant whitespace

---
 .../datastructures/buffers/CircularBufferTest.java              | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/test/java/com/thealgorithms/datastructures/buffers/CircularBufferTest.java b/src/test/java/com/thealgorithms/datastructures/buffers/CircularBufferTest.java
index 09adb07d9484..69af422e7175 100644
--- a/src/test/java/com/thealgorithms/datastructures/buffers/CircularBufferTest.java
+++ b/src/test/java/com/thealgorithms/datastructures/buffers/CircularBufferTest.java
@@ -186,7 +186,7 @@ void testFillThenEmptyThenReuseBuffer() {
     void testPutReturnsTrueOnlyIfPreviouslyEmpty() {
         CircularBuffer<String> buffer = new CircularBuffer<>(2);
 
-        assertTrue(buffer.put("one"));  // was empty
+        assertTrue(buffer.put("one")); // was empty
         org.junit.jupiter.api.Assertions.assertFalse(buffer.put("two")); // not empty
         org.junit.jupiter.api.Assertions.assertFalse(buffer.put("three")); // overwrite
     }

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