diff --git a/ext/standard/tests/filters/stream_filter_register_class_coerce_consumed_by_ref_param.phpt b/ext/standard/tests/filters/stream_filter_register_class_coerce_consumed_by_ref_param.phpt
new file mode 100644
index 00000000000..f5f0ecca797
--- /dev/null
+++ b/ext/standard/tests/filters/stream_filter_register_class_coerce_consumed_by_ref_param.phpt
@@ -0,0 +1,32 @@
+--TEST--
+stream_filter_register() with a class that coerces the $consumed parameter of filter method
+--XFAIL--
+This leaks memory
+--FILE--
+<?php
+
+class foo extends php_user_filter {
+	public function filter($in, $out, &$consumed, bool $closing): int {
+		$consumed = new stdClass();
+		return PSFS_PASS_ON;
+	}
+}
+
+var_dump(stream_filter_register("invalid_filter", "foo"));
+
+var_dump(stream_filter_append(STDOUT, "invalid_filter"));
+
+$out = fwrite(STDOUT, "Hello\n");
+var_dump($out);
+
+?>
+--EXPECTF--
+bool(true)
+resource(4) of type (stream filter)
+
+Warning: Object of class stdClass could not be converted to int in %s on line %d
+
+Warning: fwrite(): Unprocessed filter buckets remaining on input brigade in %s on line %d
+int(1)
+
+Warning: Object of class stdClass could not be converted to int in Unknown on line 0
diff --git a/ext/standard/tests/filters/stream_filter_register_class_completely_invalid.phpt b/ext/standard/tests/filters/stream_filter_register_class_completely_invalid.phpt
new file mode 100644
index 00000000000..6bd3e7bc1c9
--- /dev/null
+++ b/ext/standard/tests/filters/stream_filter_register_class_completely_invalid.phpt
@@ -0,0 +1,33 @@
+--TEST--
+stream_filter_register() with a class name that exist but does not extend php_user_filter nor mock anything
+--FILE--
+<?php
+class foo {
+
+}
+
+var_dump(stream_filter_register("invalid_filter", "foo"));
+
+var_dump(stream_filter_append(STDOUT, "invalid_filter"));
+
+$out = fwrite(STDOUT, "Hello\n");
+var_dump($out);
+
+?>
+--EXPECTF--
+bool(true)
+
+Deprecated: Creation of dynamic property foo::$filtername is deprecated in %s on line %d
+
+Deprecated: Creation of dynamic property foo::$params is deprecated in %s on line %d
+resource(%d) of type (stream filter)
+
+Warning: fwrite(): Unprocessed filter buckets remaining on input brigade in %s on line %d
+
+Fatal error: Uncaught Error: Invalid callback foo::filter, class foo does not have a method "filter" in %s:%d
+Stack trace:
+#0 %s(%d): fwrite(Resource id #%d, 'Hello\n')
+#1 {main}
+  thrown in %s on line %d
+
+Fatal error: Invalid callback foo::filter, class foo does not have a method "filter" in Unknown on line 0
diff --git a/ext/standard/tests/filters/stream_filter_register_class_completely_invalid_filtername_prop_type.phpt b/ext/standard/tests/filters/stream_filter_register_class_completely_invalid_filtername_prop_type.phpt
new file mode 100644
index 00000000000..793c112791a
--- /dev/null
+++ b/ext/standard/tests/filters/stream_filter_register_class_completely_invalid_filtername_prop_type.phpt
@@ -0,0 +1,28 @@
+--TEST--
+stream_filter_register() with a class name exist but does not extend php_user_filter and defines a $filtername prop with different type
+--FILE--
+<?php
+class foo {
+	public array $filtername;
+}
+
+var_dump(stream_filter_register("invalid_filter", "foo"));
+
+var_dump(stream_filter_append(STDOUT, "invalid_filter"));
+
+$out = fwrite(STDOUT, "Hello\n");
+var_dump($out);
+
+?>
+--EXPECTF--
+bool(true)
+
+Deprecated: Creation of dynamic property foo::$params is deprecated in %s on line %d
+
+Fatal error: Uncaught TypeError: Cannot assign string to property foo::$filtername of type array in %s:%d
+Stack trace:
+#0 %s(%d): stream_filter_append(Resource id #2, 'invalid_filter')
+#1 {main}
+  thrown in %s on line %d
+
+Fatal error: Invalid callback foo::filter, class foo does not have a method "filter" in Unknown on line 0
diff --git a/ext/standard/tests/filters/stream_filter_register_class_completely_invalid_no_dynamic_props.phpt b/ext/standard/tests/filters/stream_filter_register_class_completely_invalid_no_dynamic_props.phpt
new file mode 100644
index 00000000000..86994d5c1b6
--- /dev/null
+++ b/ext/standard/tests/filters/stream_filter_register_class_completely_invalid_no_dynamic_props.phpt
@@ -0,0 +1,28 @@
+--TEST--
+stream_filter_register() with a class name exist but does not extend php_user_filter and cannot have dynamic properties
+--FILE--
+<?php
+
+var_dump(stream_filter_register("invalid_filter", "SensitiveParameter"));
+
+var_dump(stream_filter_append(STDOUT, "invalid_filter"));
+
+$out = fwrite(STDOUT, "Hello\n");
+var_dump($out);
+
+?>
+--EXPECTF--
+bool(true)
+
+Fatal error: Uncaught Error: Cannot create dynamic property SensitiveParameter::$filtername in %s:%d
+Stack trace:
+#0 %s(%d): stream_filter_append(Resource id #%d, 'invalid_filter')
+#1 {main}
+
+Next Error: Cannot create dynamic property SensitiveParameter::$params in %s:%d
+Stack trace:
+#0 %s(%d): stream_filter_append(Resource id #%d, 'invalid_filter')
+#1 {main}
+  thrown in %s on line %d
+
+Fatal error: Invalid callback SensitiveParameter::filter, class SensitiveParameter does not have a method "filter" in Unknown on line 0
diff --git a/ext/standard/tests/filters/stream_filter_register_class_private_filtername_prop.phpt b/ext/standard/tests/filters/stream_filter_register_class_private_filtername_prop.phpt
new file mode 100644
index 00000000000..6b9be4bbbb4
--- /dev/null
+++ b/ext/standard/tests/filters/stream_filter_register_class_private_filtername_prop.phpt
@@ -0,0 +1,28 @@
+--TEST--
+stream_filter_register() with a class name exist but does not extend php_user_filter and defines a private $filtername prop
+--FILE--
+<?php
+class foo {
+	private $filtername;
+}
+
+var_dump(stream_filter_register("invalid_filter", "foo"));
+
+var_dump(stream_filter_append(STDOUT, "invalid_filter"));
+
+$out = fwrite(STDOUT, "Hello\n");
+var_dump($out);
+
+?>
+--EXPECTF--
+bool(true)
+
+Deprecated: Creation of dynamic property foo::$params is deprecated in %s on line %d
+
+Fatal error: Uncaught Error: Cannot access private property foo::$filtername in %s:%d
+Stack trace:
+#0 %s(%d): stream_filter_append(Resource id #2, 'invalid_filter')
+#1 {main}
+  thrown in %s on line %d
+
+Fatal error: Invalid callback foo::filter, class foo does not have a method "filter" in Unknown on line 0
diff --git a/ext/standard/tests/filters/stream_filter_register_class_throwing_onclose.phpt b/ext/standard/tests/filters/stream_filter_register_class_throwing_onclose.phpt
new file mode 100644
index 00000000000..76b925cc048
--- /dev/null
+++ b/ext/standard/tests/filters/stream_filter_register_class_throwing_onclose.phpt
@@ -0,0 +1,30 @@
+--TEST--
+stream_filter_register() with a class that has a onclose method that throws
+--FILE--
+<?php
+class foo extends php_user_filter {
+	public function onclose(): void {
+		throw new Exception("No");
+	}
+}
+
+var_dump(stream_filter_register("invalid_filter", "foo"));
+
+var_dump(stream_filter_append(STDOUT, "invalid_filter"));
+
+$out = fwrite(STDOUT, "Hello\n");
+var_dump($out);
+
+?>
+--EXPECTF--
+bool(true)
+resource(4) of type (stream filter)
+
+Warning: fwrite(): Unprocessed filter buckets remaining on input brigade in %s on line %d
+bool(false)
+
+Fatal error: Uncaught Exception: No in %s:%d
+Stack trace:
+#0 [internal function]: foo->onclose()
+#1 {main}
+  thrown in %s on line %d
diff --git a/ext/standard/tests/filters/stream_filter_register_class_throwing_oncreate.phpt b/ext/standard/tests/filters/stream_filter_register_class_throwing_oncreate.phpt
new file mode 100644
index 00000000000..3e429a2cc34
--- /dev/null
+++ b/ext/standard/tests/filters/stream_filter_register_class_throwing_oncreate.phpt
@@ -0,0 +1,27 @@
+--TEST--
+stream_filter_register() with a class that has a oncreate method that throws
+--FILE--
+<?php
+class foo extends php_user_filter {
+	public function oncreate(): bool {
+		throw new Exception("No");
+	}
+}
+
+var_dump(stream_filter_register("invalid_filter", "foo"));
+
+var_dump(stream_filter_append(STDOUT, "invalid_filter"));
+
+$out = fwrite(STDOUT, "Hello\n");
+var_dump($out);
+
+?>
+--EXPECTF--
+bool(true)
+
+Fatal error: Uncaught Exception: No in %s:%d
+Stack trace:
+#0 [internal function]: foo->oncreate()
+#1 %s(%d): stream_filter_append(Resource id #2, 'invalid_filter')
+#2 {main}
+  thrown in %s on line %d
diff --git a/ext/standard/tests/filters/stream_filter_register_filter_always_feed.phpt b/ext/standard/tests/filters/stream_filter_register_filter_always_feed.phpt
new file mode 100644
index 00000000000..7a3d3f88999
--- /dev/null
+++ b/ext/standard/tests/filters/stream_filter_register_filter_always_feed.phpt
@@ -0,0 +1,24 @@
+--TEST--
+stream_filter_register() with a filter method always returning PSFS_FEED_ME
+--FILE--
+<?php
+class foo extends php_user_filter {
+	public function filter($in, $out, &$consumed, bool $closing): int {
+		return PSFS_FEED_ME;
+	}
+}
+
+var_dump(stream_filter_register("invalid_filter", "foo"));
+
+var_dump(stream_filter_append(STDOUT, "invalid_filter"));
+
+$out = fwrite(STDOUT, "Hello\n");
+var_dump($out);
+
+?>
+--EXPECTF--
+bool(true)
+resource(4) of type (stream filter)
+
+Warning: fwrite(): Unprocessed filter buckets remaining on input brigade in %s on line %d
+int(0)
diff --git a/ext/standard/tests/filters/stream_filter_register_mock_class_filter.phpt b/ext/standard/tests/filters/stream_filter_register_mock_class_filter.phpt
new file mode 100644
index 00000000000..4d2309a718e
--- /dev/null
+++ b/ext/standard/tests/filters/stream_filter_register_mock_class_filter.phpt
@@ -0,0 +1,30 @@
+--TEST--
+stream_filter_register() with a class name exist that mocks php_user_filter with a filter method
+--XFAIL--
+This leaks memory
+--FILE--
+<?php
+
+class foo {
+	public $filtername;
+	public $params;
+
+	public function filter($in, $out, &$consumed, bool $closing): int {
+		return PSFS_PASS_ON;
+	}
+}
+
+var_dump(stream_filter_register("invalid_filter", "foo"));
+
+var_dump(stream_filter_append(STDOUT, "invalid_filter"));
+
+$out = fwrite(STDOUT, "Hello\n");
+var_dump($out);
+
+?>
+--EXPECTF--
+bool(true)
+resource(4) of type (stream filter)
+
+Warning: fwrite(): Unprocessed filter buckets remaining on input brigade in %s on line %d
+int(0)
diff --git a/ext/standard/tests/filters/stream_filter_register_mock_class_filter_incorect_return_type.phpt b/ext/standard/tests/filters/stream_filter_register_mock_class_filter_incorect_return_type.phpt
new file mode 100644
index 00000000000..b5ec8da3dde
--- /dev/null
+++ b/ext/standard/tests/filters/stream_filter_register_mock_class_filter_incorect_return_type.phpt
@@ -0,0 +1,32 @@
+--TEST--
+stream_filter_register() with a class name exist that mocks php_user_filter with a filter method returning not an int
+--FILE--
+<?php
+
+class foo {
+	public $filtername;
+	public $params;
+
+	public function filter($in, $out, &$consumed, bool $closing) {
+		return new stdClass();
+	}
+}
+
+var_dump(stream_filter_register("invalid_filter", "foo"));
+
+var_dump(stream_filter_append(STDOUT, "invalid_filter"));
+
+$out = fwrite(STDOUT, "Hello\n");
+var_dump($out);
+
+?>
+--EXPECTF--
+bool(true)
+resource(4) of type (stream filter)
+
+Warning: Object of class stdClass could not be converted to int in %s on line %d
+
+Warning: fwrite(): Unprocessed filter buckets remaining on input brigade in %s on line %d
+int(0)
+
+Warning: Object of class stdClass could not be converted to int in Unknown on line 0
diff --git a/ext/standard/tests/filters/stream_filter_register_mock_class_filter_is_private.phpt b/ext/standard/tests/filters/stream_filter_register_mock_class_filter_is_private.phpt
new file mode 100644
index 00000000000..6abffe1ff5f
--- /dev/null
+++ b/ext/standard/tests/filters/stream_filter_register_mock_class_filter_is_private.phpt
@@ -0,0 +1,35 @@
+--TEST--
+stream_filter_register() with a class name exist that mocks php_user_filter with a private filter method
+--FILE--
+<?php
+
+class foo {
+	public $filtername;
+	public $params;
+
+	private function filter($in, $out, &$consumed, bool $closing): int {
+		return PSFS_PASS_ON;
+	}
+}
+
+var_dump(stream_filter_register("invalid_filter", "foo"));
+
+var_dump(stream_filter_append(STDOUT, "invalid_filter"));
+
+$out = fwrite(STDOUT, "Hello\n");
+var_dump($out);
+
+?>
+--EXPECTF--
+bool(true)
+resource(%d) of type (stream filter)
+
+Warning: fwrite(): Unprocessed filter buckets remaining on input brigade in %s on line %d
+
+Fatal error: Uncaught Error: Invalid callback foo::filter, cannot access private method foo::filter() in %s:%d
+Stack trace:
+#0 %s(%d): fwrite(Resource id #%d, 'Hello\n')
+#1 {main}
+  thrown in %s on line %d
+
+Fatal error: Invalid callback foo::filter, cannot access private method foo::filter() in Unknown on line 0
diff --git a/ext/standard/tests/filters/stream_filter_register_non_existing_class.phpt b/ext/standard/tests/filters/stream_filter_register_non_existing_class.phpt
new file mode 100644
index 00000000000..1c08201cff0
--- /dev/null
+++ b/ext/standard/tests/filters/stream_filter_register_non_existing_class.phpt
@@ -0,0 +1,21 @@
+--TEST--
+stream_filter_register() with a class name that does not exist
+--FILE--
+<?php
+
+var_dump(stream_filter_register("not_existing_filter", "not_existing"));
+
+stream_filter_append(STDOUT, "not_existing_filter");
+
+$out = fwrite(STDOUT, "Hello\n");
+var_dump($out);
+
+?>
+--EXPECTF--
+bool(true)
+
+Warning: stream_filter_append(): User-filter "not_existing_filter" requires class "not_existing", but that class is not defined in %s on line %d
+
+Warning: stream_filter_append(): Unable to create or locate filter "not_existing_filter" in %s on line %d
+Hello
+int(6)