diff -r d31f4d4075dc -r 0e1cf2cd500e tests/test_hash_key.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test_hash_key.c	Wed Dec 20 18:13:30 2023 +0100
@@ -0,0 +1,97 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ *
+ * Copyright 2023 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/test.h"
+
+#include "cx/hash_key.h"
+#include "cx/string.h"
+
+CX_TEST(test_hash_key_functions) {
+    char const* str = "my key";
+    size_t len = strlen(str);
+
+    CxHashKey str_key = cx_hash_key_str(str);
+    CxHashKey bytes_key = cx_hash_key_bytes((unsigned char const*)str, len);
+    CxHashKey obj_key = cx_hash_key(str, len);
+    CxHashKey cxstr_key = cx_hash_key_cxstr(cx_str(str));
+
+    CX_TEST_DO {
+        CX_TEST_ASSERT(str_key.hash == bytes_key.hash);
+        CX_TEST_ASSERT(obj_key.hash == bytes_key.hash);
+        CX_TEST_ASSERT(cxstr_key.hash == bytes_key.hash);
+        CX_TEST_ASSERT(str_key.len == len);
+        CX_TEST_ASSERT(cxstr_key.len == len);
+        CX_TEST_ASSERT(bytes_key.len == len);
+        CX_TEST_ASSERT(bytes_key.len == len);
+        CX_TEST_ASSERT(str_key.data == str);
+    }
+}
+
+CX_TEST(test_hash_key_empty_string) {
+    char const* str = "";
+
+    CxHashKey str_key = cx_hash_key_str(str);
+    CxHashKey bytes_key = cx_hash_key_bytes((unsigned char const*) str, 0);
+    CxHashKey obj_key = cx_hash_key(str, 0);
+
+    CX_TEST_DO {
+        CX_TEST_ASSERT(bytes_key.hash == 4152238450u);
+        CX_TEST_ASSERT(str_key.hash == 4152238450u);
+        CX_TEST_ASSERT(obj_key.hash == 4152238450u);
+        CX_TEST_ASSERT(str_key.len == 0);
+        CX_TEST_ASSERT(bytes_key.len == 0);
+        CX_TEST_ASSERT(bytes_key.len == 0);
+        CX_TEST_ASSERT(str_key.data == str);
+    }
+}
+
+CX_TEST(test_hash_key_null) {
+    CxHashKey str_key = cx_hash_key_str(NULL);
+    CxHashKey bytes_key = cx_hash_key_bytes(NULL, 0);
+    CxHashKey obj_key = cx_hash_key(NULL, 0);
+
+    CX_TEST_DO {
+        CX_TEST_ASSERT(bytes_key.hash == 1574210520u);
+        CX_TEST_ASSERT(str_key.hash == 1574210520u);
+        CX_TEST_ASSERT(obj_key.hash == 1574210520u);
+        CX_TEST_ASSERT(str_key.len == 0);
+        CX_TEST_ASSERT(bytes_key.len == 0);
+        CX_TEST_ASSERT(bytes_key.len == 0);
+        CX_TEST_ASSERT(str_key.data == NULL);
+    }
+}
+
+CxTestSuite *cx_test_suite_hash_key(void) {
+    CxTestSuite *suite = cx_test_suite_new("hash_key");
+
+    cx_test_register(suite, test_hash_key_functions);
+    cx_test_register(suite, test_hash_key_empty_string);
+    cx_test_register(suite, test_hash_key_null);
+
+    return suite;
+}