diff -r 2e6e9d9f2159 -r c9d008861178 tests/test_allocator.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test_allocator.cpp	Wed Feb 08 20:26:26 2023 +0100
@@ -0,0 +1,96 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ *
+ * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   1. Redistributions of source code must retain the above copyright
+ *      notice, this list of conditions and the following disclaimer.
+ *
+ *   2. Redistributions in binary form must reproduce the above copyright
+ *      notice, this list of conditions and the following disclaimer in the
+ *      documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "cx/allocator.h"
+#include <gtest/gtest.h>
+
+TEST(Allocator, DefaultAllocator) {
+    cx_allocator_class *clazz = cxDefaultAllocator->cl;
+    ASSERT_NE(clazz, nullptr);
+}
+
+TEST(Allocator, DefaultMalloc) {
+    void *test = cxMalloc(cxDefaultAllocator, 16);
+    ASSERT_NE(test, nullptr);
+    free(test);
+}
+
+TEST(Allocator, DefaultRealloc) {
+    void *test = calloc(8, 1);
+    memcpy(test, "Test", 5);
+    test = cxRealloc(cxDefaultAllocator, test, 16);
+    ASSERT_NE(test, nullptr);
+    EXPECT_STREQ(reinterpret_cast<char *>(test), "Test");
+    free(test);
+}
+
+TEST(Allocator, Reallocate) {
+    void *test = calloc(8, 1);
+    memcpy(test, "Test", 5);
+    int ret = cxReallocate(cxDefaultAllocator, &test, 16);
+    EXPECT_EQ(ret, 0);
+    ASSERT_NE(test, nullptr);
+    EXPECT_STREQ(reinterpret_cast<char *>(test), "Test");
+    free(test);
+}
+
+TEST(Allocator, DefaultCalloc) {
+    char *test = reinterpret_cast<char *>(cxCalloc(cxDefaultAllocator, 8, 2));
+    ASSERT_NE(test, nullptr);
+    for (int i = 0; i < 16; i++) ASSERT_EQ(test[i], 0);
+    free(test);
+}
+
+TEST(Allocator, DefaultFree) {
+    void *test = malloc(16);
+    EXPECT_NO_FATAL_FAILURE(
+            cxFree(cxDefaultAllocator, test);
+    );
+}
+
+TEST(Allocator, FailingReallocate) {
+    // Mock an allocator that always returns nullptr on realloc
+    cx_allocator_class mock_cl;
+    mock_cl.realloc = [](
+            [[maybe_unused]]void *p,
+            [[maybe_unused]]void *d,
+            [[maybe_unused]]size_t n
+    ) -> void * { return nullptr; };
+    cx_allocator_s mock{&mock_cl, nullptr};
+
+    void *test = calloc(8, 1);
+    memcpy(test, "Test", 5);
+    void *original = test;
+    int ret = cxReallocate(&mock, &test, 16);
+    // non-zero return code because of the failure
+    EXPECT_NE(ret, 0);
+    // the test pointer was not changed and still points to the same memory
+    EXPECT_EQ(test, original);
+    EXPECT_STREQ(reinterpret_cast<char *>(test), "Test");
+    free(test);
+}