test: add unit tests for CircularFifoQueue

sentry/src/test/java/io/sentry/CircularFifoQueueTest.kt

@@ -0,0 +1,224 @@
+package io.sentry
+
+import java.util.NoSuchElementException
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFailsWith
+import kotlin.test.assertFalse
+import kotlin.test.assertNull
+import kotlin.test.assertTrue
+
+class CircularFifoQueueTest {
+
+  @Test
+  fun `constructor with size creates empty queue with given max size`() {
+    val queue = CircularFifoQueue<String>(5)
+    assertEquals(0, queue.size)
+    assertEquals(5, queue.maxSize())
+    assertTrue(queue.isEmpty())
+  }
+
+  @Test
+  fun `constructor rejects zero size`() {
+    assertFailsWith<IllegalArgumentException> { CircularFifoQueue<String>(0) }
+  }
+
+  @Test
+  fun `constructor rejects negative size`() {
+    assertFailsWith<IllegalArgumentException> { CircularFifoQueue<String>(-1) }
+  }
+
+  @Test
+  fun `default constructor creates queue with max size 32`() {
+    val queue = CircularFifoQueue<String>()
+    assertEquals(32, queue.maxSize())
+  }
+
+  @Test
+  fun `add increases size`() {
+    val queue = CircularFifoQueue<String>(3)
+    queue.add("a")
+    assertEquals(1, queue.size)
+    queue.add("b")
+    assertEquals(2, queue.size)
+  }
+
+  @Test
+  fun `peek returns first element without removing it`() {
+    val queue = CircularFifoQueue<String>(3)
+    queue.add("a")
+    queue.add("b")
+    assertEquals("a", queue.peek())
+    assertEquals(2, queue.size)
+  }
+
+  @Test
+  fun `peek returns null on empty queue`() {
+    val queue = CircularFifoQueue<String>(3)
+    assertNull(queue.peek())
+  }
+
+  @Test
+  fun `poll removes and returns first element`() {
+    val queue = CircularFifoQueue<String>(3)
+    queue.add("a")
+    queue.add("b")
+    assertEquals("a", queue.poll())
+    assertEquals(1, queue.size)
+  }
+
+  @Test
+  fun `poll returns null on empty queue`() {
+    val queue = CircularFifoQueue<String>(3)
+    assertNull(queue.poll())
+  }
+
+  @Test
+  fun `remove throws on empty queue`() {
+    val queue = CircularFifoQueue<String>(3)
+    assertFailsWith<NoSuchElementException> { queue.remove() }
+  }
+
+  @Test
+  fun `element throws on empty queue`() {
+    val queue = CircularFifoQueue<String>(3)
+    assertFailsWith<NoSuchElementException> { queue.element() }
+  }
+
+  @Test
+  fun `element returns first element without removing it`() {
+    val queue = CircularFifoQueue<String>(3)
+    queue.add("a")
+    assertEquals("a", queue.element())
+    assertEquals(1, queue.size)
+  }
+
+  @Test
+  fun `overflow evicts oldest element`() {
+    val queue = CircularFifoQueue<String>(3)
+    queue.add("a")
+    queue.add("b")
+    queue.add("c")
+    queue.add("d") // evicts "a"
+    assertEquals(3, queue.size)
+    assertEquals("b", queue.peek())
+  }
+
+  @Test
+  fun `isAtFullCapacity returns true when queue is full`() {
+    val queue = CircularFifoQueue<String>(2)
+    assertFalse(queue.isAtFullCapacity)
+    queue.add("a")
+    assertFalse(queue.isAtFullCapacity)
+    queue.add("b")
+    assertTrue(queue.isAtFullCapacity)
+  }
+
+  @Test
+  fun `isFull always returns false`() {
+    val queue = CircularFifoQueue<String>(2)
+    assertFalse(queue.isFull)
+    queue.add("a")
+    queue.add("b")
+    assertFalse(queue.isFull)
+  }
+
+  @Test
+  fun `get returns element at index`() {
+    val queue = CircularFifoQueue<String>(5)
+    queue.add("a")
+    queue.add("b")
+    queue.add("c")
+    assertEquals("a", queue.get(0))
+    assertEquals("b", queue.get(1))
+    assertEquals("c", queue.get(2))
+  }
+
+  @Test
+  fun `get throws for negative index`() {
+    val queue = CircularFifoQueue<String>(3)
+    queue.add("a")
+    assertFailsWith<NoSuchElementException> { queue.get(-1) }
+  }
+
+  @Test
+  fun `get throws for index out of range`() {
+    val queue = CircularFifoQueue<String>(3)
+    queue.add("a")
+    assertFailsWith<NoSuchElementException> { queue.get(1) }
+  }
+
+  @Test
+  fun `clear resets the queue`() {
+    val queue = CircularFifoQueue<String>(3)
+    queue.add("a")
+    queue.add("b")
+    queue.clear()
+    assertEquals(0, queue.size)
+    assertTrue(queue.isEmpty())
+    assertNull(queue.peek())
+  }
+
+  @Test
+  fun `iterator returns elements in insertion order`() {
+    val queue = CircularFifoQueue<String>(5)
+    queue.add("a")
+    queue.add("b")
+    queue.add("c")
+    assertEquals(listOf("a", "b", "c"), queue.toList())
+  }
+
+  @Test
+  fun `iterator returns elements in order after overflow`() {
+    val queue = CircularFifoQueue<String>(3)
+    queue.add("a")
+    queue.add("b")
+    queue.add("c")
+    queue.add("d") // evicts "a"
+    queue.add("e") // evicts "b"
+    assertEquals(listOf("c", "d", "e"), queue.toList())
+  }
+
+  @Test
+  fun `offer delegates to add`() {
+    val queue = CircularFifoQueue<String>(3)
+    assertTrue(queue.offer("a"))
+    assertEquals(1, queue.size)
+    assertEquals("a", queue.peek())
+  }
+
+  @Test
+  fun `constructor from collection copies elements`() {
+    val source = listOf("a", "b", "c")
+    val queue = CircularFifoQueue(source)
+    assertEquals(3, queue.size)
+    assertEquals(3, queue.maxSize())
+    assertEquals(listOf("a", "b", "c"), queue.toList())
+  }
+
+  @Test
+  fun `get works correctly after wrap-around`() {
+    val queue = CircularFifoQueue<String>(3)
+    queue.add("a")
+    queue.add("b")
+    queue.add("c")
+    queue.add("d") // wraps: [d, b, c] with start=1
+    assertEquals("b", queue.get(0))
+    assertEquals("c", queue.get(1))
+    assertEquals("d", queue.get(2))
+  }
+
+  @Test
+  fun `multiple add and remove cycles work correctly`() {
+    val queue = CircularFifoQueue<String>(3)
+    queue.add("a")
+    queue.add("b")
+    assertEquals("a", queue.remove())
+    queue.add("c")
+    queue.add("d")
+    assertEquals("b", queue.remove())
+    assertEquals("c", queue.remove())
+    assertEquals("d", queue.remove())
+    assertTrue(queue.isEmpty())
+  }
+}