diff --git a/tests/std/core/001_strcmp.phpt b/tests/std/core/001_strcmp.phpt
new file mode 100644
index 00000000..315e927a
--- /dev/null
+++ b/tests/std/core/001_strcmp.phpt
@@ -0,0 +1,41 @@
+--TEST--
+strcmp() / strncmp() / strcasecmp() / strncasecmp() functions
+--FILE--
+<?php
+
+echo "strcmp:\n";
+echo strcmp("abc", "abc") === 0 ? "ok-equal\n" : "fail\n";
+echo strcmp("abc", "abd") < 0 ? "ok-less\n" : "fail\n";
+echo strcmp("abd", "abc") > 0 ? "ok-greater\n" : "fail\n";
+echo strcmp("", "") === 0 ? "ok-empty\n" : "fail\n";
+
+echo "strncmp:\n";
+echo strncmp("abcdef", "abcxyz", 3) === 0 ? "ok-equal3\n" : "fail\n";
+echo strncmp("abcdef", "abcxyz", 6) < 0 ? "ok-less6\n" : "fail\n";
+echo strncmp("abc", "abc", 5) === 0 ? "ok-overflow\n" : "fail\n";
+
+echo "strcasecmp:\n";
+echo strcasecmp("ABC", "abc") === 0 ? "ok-equal\n" : "fail\n";
+echo strcasecmp("ABC", "abd") < 0 ? "ok-less\n" : "fail\n";
+
+echo "strncasecmp:\n";
+echo strncasecmp("ABCDEF", "abcxyz", 3) === 0 ? "ok-equal3\n" : "fail\n";
+echo strncasecmp("ABCDEF", "abcxyz", 6) < 0 ? "ok-less6\n" : "fail\n";
+
+?>
+--EXPECT--
+strcmp:
+ok-equal
+ok-less
+ok-greater
+ok-empty
+strncmp:
+ok-equal3
+ok-less6
+ok-overflow
+strcasecmp:
+ok-equal
+ok-less
+strncasecmp:
+ok-equal3
+ok-less6
diff --git a/tests/std/core/002_class_exists.phpt b/tests/std/core/002_class_exists.phpt
new file mode 100644
index 00000000..4c4c81c5
--- /dev/null
+++ b/tests/std/core/002_class_exists.phpt
@@ -0,0 +1,42 @@
+--TEST--
+class_exists() / interface_exists() / trait_exists() / enum_exists() functions
+--FILE--
+<?php
+
+class MyClass {}
+interface MyInterface {}
+trait MyTrait {}
+enum MyEnum { case A; }
+
+echo "class_exists:\n";
+echo class_exists("MyClass") ? "ok-true\n" : "fail\n";
+echo class_exists("NonExistentClass") ? "fail\n" : "ok-false\n";
+
+echo "interface_exists:\n";
+echo interface_exists("MyInterface") ? "ok-true\n" : "fail\n";
+echo interface_exists("NonExistentInterface") ? "fail\n" : "ok-false\n";
+
+echo "trait_exists:\n";
+echo trait_exists("MyTrait") ? "ok-true\n" : "fail\n";
+echo trait_exists("NonExistentTrait") ? "fail\n" : "ok-false\n";
+
+echo "enum_exists:\n";
+echo enum_exists("MyEnum") ? "ok-true\n" : "fail\n";
+echo enum_exists("NonExistentEnum") ? "fail\n" : "ok-false\n";
+
+echo "done\n";
+?>
+--EXPECT--
+class_exists:
+ok-true
+ok-false
+interface_exists:
+ok-true
+ok-false
+trait_exists:
+ok-true
+ok-false
+enum_exists:
+ok-true
+ok-false
+done
diff --git a/tests/std/core/003_method_exists.phpt b/tests/std/core/003_method_exists.phpt
new file mode 100644
index 00000000..8e7cc7e8
--- /dev/null
+++ b/tests/std/core/003_method_exists.phpt
@@ -0,0 +1,47 @@
+--TEST--
+method_exists() / property_exists() functions
+--FILE--
+<?php
+
+class TestClass {
+    public int $pubProp = 0;
+    private string $privProp = "secret";
+
+    public function pubMethod(): string { return "public"; }
+    private function privMethod(): string { return "private"; }
+}
+
+$obj = new TestClass();
+
+echo "method_exists:\n";
+echo method_exists($obj, "pubMethod") ? "ok-obj-pub\n" : "fail\n";
+echo method_exists($obj, "privMethod") ? "ok-obj-priv\n" : "fail\n";
+echo method_exists($obj, "noSuchMethod") ? "fail\n" : "ok-obj-none\n";
+echo method_exists(TestClass::class, "pubMethod") ? "ok-cls-pub\n" : "fail\n";
+echo method_exists(TestClass::class, "noSuchMethod") ? "fail\n" : "ok-cls-none\n";
+
+echo "property_exists:\n";
+echo property_exists($obj, "pubProp") ? "ok-obj-pub\n" : "fail\n";
+echo property_exists($obj, "privProp") ? "ok-obj-priv\n" : "fail\n";
+echo property_exists($obj, "noSuchProp") ? "fail\n" : "ok-obj-none\n";
+echo property_exists(TestClass::class, "pubProp") ? "ok-cls-pub\n" : "fail\n";
+echo property_exists(TestClass::class, "privProp") ? "ok-cls-priv\n" : "fail\n";
+echo property_exists(TestClass::class, "noSuchProp") ? "fail\n" : "ok-cls-none\n";
+
+echo "done\n";
+?>
+--EXPECT--
+method_exists:
+ok-obj-pub
+ok-obj-priv
+ok-obj-none
+ok-cls-pub
+ok-cls-none
+property_exists:
+ok-obj-pub
+ok-obj-priv
+ok-obj-none
+ok-cls-pub
+ok-cls-priv
+ok-cls-none
+done
diff --git a/tests/std/core/004_is_a.phpt b/tests/std/core/004_is_a.phpt
new file mode 100644
index 00000000..f58c8d8a
--- /dev/null
+++ b/tests/std/core/004_is_a.phpt
@@ -0,0 +1,39 @@
+--TEST--
+is_a() / is_subclass_of() functions
+--FILE--
+<?php
+
+class Base {}
+class Child extends Base {}
+interface IFace {}
+class Impl implements IFace {}
+
+$child = new Child();
+$impl = new Impl();
+
+echo "is_a:\n";
+echo is_a($child, "Child") ? "ok-obj-class\n" : "fail\n";
+echo is_a($child, "Base") ? "ok-obj-parent\n" : "fail\n";
+echo is_a($child, "NoSuchClass") ? "fail\n" : "ok-obj-none\n";
+
+echo "is_subclass_of:\n";
+echo is_subclass_of($child, "Base") ? "ok-obj-parent\n" : "fail\n";
+echo is_subclass_of($child, "Child") ? "fail\n" : "ok-obj-same\n";
+echo is_subclass_of(Child::class, "Base") ? "ok-cls-parent\n" : "fail\n";
+echo is_subclass_of(Child::class, "Child") ? "fail\n" : "ok-cls-same\n";
+echo is_subclass_of($child, "NoSuchClass") ? "fail\n" : "ok-none\n";
+
+echo "done\n";
+?>
+--EXPECT--
+is_a:
+ok-obj-class
+ok-obj-parent
+ok-obj-none
+is_subclass_of:
+ok-obj-parent
+ok-obj-same
+ok-cls-parent
+ok-cls-same
+ok-none
+done
diff --git a/tests/std/core/005_defined.phpt b/tests/std/core/005_defined.phpt
new file mode 100644
index 00000000..485b0135
--- /dev/null
+++ b/tests/std/core/005_defined.phpt
@@ -0,0 +1,23 @@
+--TEST--
+defined() function
+--FILE--
+<?php
+
+define("MY_CONST", 42);
+define("MY_STRING_CONST", "hello");
+
+echo "defined:\n";
+echo defined("MY_CONST") ? "ok-defined\n" : "fail\n";
+echo defined("MY_STRING_CONST") ? "ok-string-defined\n" : "fail\n";
+echo defined("PHP_VERSION") ? "ok-php-version\n" : "fail\n";
+echo defined("NON_EXISTENT") ? "fail\n" : "ok-undefined\n";
+
+echo "done\n";
+?>
+--EXPECT--
+defined:
+ok-defined
+ok-string-defined
+ok-php-version
+ok-undefined
+done
diff --git a/tests/std/core/006_get_parent_class.phpt b/tests/std/core/006_get_parent_class.phpt
new file mode 100644
index 00000000..b5679859
--- /dev/null
+++ b/tests/std/core/006_get_parent_class.phpt
@@ -0,0 +1,27 @@
+--TEST--
+get_parent_class() function
+--FILE--
+<?php
+
+class Base {}
+class Child extends Base {}
+class NoParent {}
+
+$child = new Child();
+$noParent = new NoParent();
+
+echo "get_parent_class:\n";
+echo get_parent_class($child) === "Base" ? "ok-obj\n" : "fail-obj\n";
+echo get_parent_class(Child::class) === "Base" ? "ok-cls\n" : "fail-cls\n";
+echo get_parent_class($noParent) === false ? "ok-obj-false\n" : "fail-obj-false\n";
+echo get_parent_class(NoParent::class) === false ? "ok-cls-false\n" : "fail-cls-false\n";
+
+echo "done\n";
+?>
+--EXPECT--
+get_parent_class:
+ok-obj
+ok-cls
+ok-obj-false
+ok-cls-false
+done