diff --git a/tests/core/io/test_stream_peer.h b/tests/core/io/test_stream_peer.h
new file mode 100644
index 00000000000..31bd69edd0a
--- /dev/null
+++ b/tests/core/io/test_stream_peer.h
@@ -0,0 +1,289 @@
+/**************************************************************************/
+/*  test_stream_peer.h                                                    */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#ifndef TEST_STREAM_PEER_H
+#define TEST_STREAM_PEER_H
+
+#include "core/io/stream_peer.h"
+#include "tests/test_macros.h"
+
+namespace TestStreamPeer {
+
+TEST_CASE("[StreamPeer] Initialization through StreamPeerBuffer") {
+	Ref<StreamPeerBuffer> spb;
+	spb.instantiate();
+
+	CHECK_EQ(spb->is_big_endian_enabled(), false);
+}
+
+TEST_CASE("[StreamPeer] Get and sets through StreamPeerBuffer") {
+	Ref<StreamPeerBuffer> spb;
+	spb.instantiate();
+
+	SUBCASE("A int8_t value") {
+		int8_t value = 42;
+
+		spb->clear();
+		spb->put_8(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_8(), value);
+	}
+
+	SUBCASE("A uint8_t value") {
+		uint8_t value = 42;
+
+		spb->clear();
+		spb->put_u8(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_u8(), value);
+	}
+
+	SUBCASE("A int16_t value") {
+		int16_t value = 42;
+
+		spb->clear();
+		spb->put_16(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_16(), value);
+	}
+
+	SUBCASE("A uint16_t value") {
+		uint16_t value = 42;
+
+		spb->clear();
+		spb->put_u16(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_u16(), value);
+	}
+
+	SUBCASE("A int32_t value") {
+		int32_t value = 42;
+
+		spb->clear();
+		spb->put_32(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_32(), value);
+	}
+
+	SUBCASE("A uint32_t value") {
+		uint32_t value = 42;
+
+		spb->clear();
+		spb->put_u32(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_u32(), value);
+	}
+
+	SUBCASE("A int64_t value") {
+		int64_t value = 42;
+
+		spb->clear();
+		spb->put_64(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_64(), value);
+	}
+
+	SUBCASE("A int64_t value") {
+		uint64_t value = 42;
+
+		spb->clear();
+		spb->put_u64(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_u64(), value);
+	}
+
+	SUBCASE("A float value") {
+		float value = 42.0f;
+
+		spb->clear();
+		spb->put_float(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_float(), value);
+	}
+
+	SUBCASE("A double value") {
+		double value = 42.0;
+
+		spb->clear();
+		spb->put_double(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_double(), value);
+	}
+
+	SUBCASE("A string value") {
+		String value = "Hello, World!";
+
+		spb->clear();
+		spb->put_string(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_string(), value);
+	}
+
+	SUBCASE("A utf8 string value") {
+		String value = String::utf8("Hello✩, World✩!");
+
+		spb->clear();
+		spb->put_utf8_string(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_utf8_string(), value);
+	}
+
+	SUBCASE("A variant value") {
+		Array value;
+		value.push_front(42);
+		value.push_front("Hello, World!");
+
+		spb->clear();
+		spb->put_var(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_var(), value);
+	}
+}
+
+TEST_CASE("[StreamPeer] Get and sets big endian through StreamPeerBuffer") {
+	Ref<StreamPeerBuffer> spb;
+	spb.instantiate();
+	spb->set_big_endian(true);
+
+	SUBCASE("A int16_t value") {
+		int16_t value = 42;
+
+		spb->clear();
+		spb->put_16(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_16(), value);
+	}
+
+	SUBCASE("A uint16_t value") {
+		uint16_t value = 42;
+
+		spb->clear();
+		spb->put_u16(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_u16(), value);
+	}
+
+	SUBCASE("A int32_t value") {
+		int32_t value = 42;
+
+		spb->clear();
+		spb->put_32(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_32(), value);
+	}
+
+	SUBCASE("A uint32_t value") {
+		uint32_t value = 42;
+
+		spb->clear();
+		spb->put_u32(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_u32(), value);
+	}
+
+	SUBCASE("A int64_t value") {
+		int64_t value = 42;
+
+		spb->clear();
+		spb->put_64(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_64(), value);
+	}
+
+	SUBCASE("A int64_t value") {
+		uint64_t value = 42;
+
+		spb->clear();
+		spb->put_u64(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_u64(), value);
+	}
+
+	SUBCASE("A float value") {
+		float value = 42.0f;
+
+		spb->clear();
+		spb->put_float(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_float(), value);
+	}
+
+	SUBCASE("A double value") {
+		double value = 42.0;
+
+		spb->clear();
+		spb->put_double(value);
+		spb->seek(0);
+
+		CHECK_EQ(spb->get_double(), value);
+	}
+}
+
+TEST_CASE("[StreamPeer] Get string when there is no string") {
+	Ref<StreamPeerBuffer> spb;
+	spb.instantiate();
+
+	ERR_PRINT_OFF;
+	CHECK_EQ(spb->get_string(), "");
+	ERR_PRINT_ON;
+}
+
+TEST_CASE("[StreamPeer] Get UTF8 string when there is no string") {
+	Ref<StreamPeerBuffer> spb;
+	spb.instantiate();
+
+	ERR_PRINT_OFF;
+	CHECK_EQ(spb->get_utf8_string(), "");
+	ERR_PRINT_ON;
+}
+
+} // namespace TestStreamPeer
+
+#endif // TEST_STREAM_PEER_H
diff --git a/tests/core/io/test_stream_peer_buffer.h b/tests/core/io/test_stream_peer_buffer.h
new file mode 100644
index 00000000000..8ba9c0a72cb
--- /dev/null
+++ b/tests/core/io/test_stream_peer_buffer.h
@@ -0,0 +1,185 @@
+/**************************************************************************/
+/*  test_stream_peer_buffer.h                                             */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#ifndef TEST_STREAM_PEER_BUFFER_H
+#define TEST_STREAM_PEER_BUFFER_H
+
+#include "core/io/stream_peer.h"
+#include "tests/test_macros.h"
+
+namespace TestStreamPeerBuffer {
+
+TEST_CASE("[StreamPeerBuffer] Initialization") {
+	Ref<StreamPeerBuffer> spb;
+	spb.instantiate();
+	CHECK_EQ(spb->get_size(), 0);
+	CHECK_EQ(spb->get_position(), 0);
+	CHECK_EQ(spb->get_available_bytes(), 0);
+}
+
+TEST_CASE("[StreamPeerBuffer] Seek") {
+	Ref<StreamPeerBuffer> spb;
+	spb.instantiate();
+	uint8_t first = 5;
+	uint8_t second = 7;
+	uint8_t third = 11;
+
+	spb->put_u8(first);
+	spb->put_u8(second);
+	spb->put_u8(third);
+
+	spb->seek(0);
+	CHECK_EQ(spb->get_u8(), first);
+	CHECK_EQ(spb->get_u8(), second);
+	CHECK_EQ(spb->get_u8(), third);
+
+	spb->seek(1);
+	CHECK_EQ(spb->get_position(), 1);
+	CHECK_EQ(spb->get_u8(), second);
+
+	spb->seek(1);
+	ERR_PRINT_OFF;
+	spb->seek(-1);
+	ERR_PRINT_ON;
+	CHECK_EQ(spb->get_position(), 1);
+	ERR_PRINT_OFF;
+	spb->seek(5);
+	ERR_PRINT_ON;
+	CHECK_EQ(spb->get_position(), 1);
+}
+
+TEST_CASE("[StreamPeerBuffer] Resize") {
+	Ref<StreamPeerBuffer> spb;
+	spb.instantiate();
+	CHECK_EQ(spb->get_size(), 0);
+	CHECK_EQ(spb->get_position(), 0);
+	CHECK_EQ(spb->get_available_bytes(), 0);
+
+	spb->resize(42);
+	CHECK_EQ(spb->get_size(), 42);
+	CHECK_EQ(spb->get_position(), 0);
+	CHECK_EQ(spb->get_available_bytes(), 42);
+
+	spb->seek(21);
+	CHECK_EQ(spb->get_size(), 42);
+	CHECK_EQ(spb->get_position(), 21);
+	CHECK_EQ(spb->get_available_bytes(), 21);
+}
+
+TEST_CASE("[StreamPeerBuffer] Get underlying data array") {
+	uint8_t first = 5;
+	uint8_t second = 7;
+	uint8_t third = 11;
+
+	Ref<StreamPeerBuffer> spb;
+	spb.instantiate();
+	spb->put_u8(first);
+	spb->put_u8(second);
+	spb->put_u8(third);
+
+	Vector<uint8_t> data_array = spb->get_data_array();
+
+	CHECK_EQ(data_array[0], first);
+	CHECK_EQ(data_array[1], second);
+	CHECK_EQ(data_array[2], third);
+}
+
+TEST_CASE("[StreamPeerBuffer] Set underlying data array") {
+	uint8_t first = 5;
+	uint8_t second = 7;
+	uint8_t third = 11;
+
+	Ref<StreamPeerBuffer> spb;
+	spb.instantiate();
+	spb->put_u8(1);
+	spb->put_u8(2);
+	spb->put_u8(3);
+
+	Vector<uint8_t> new_data_array;
+	new_data_array.push_back(first);
+	new_data_array.push_back(second);
+	new_data_array.push_back(third);
+
+	spb->set_data_array(new_data_array);
+
+	CHECK_EQ(spb->get_u8(), first);
+	CHECK_EQ(spb->get_u8(), second);
+	CHECK_EQ(spb->get_u8(), third);
+}
+
+TEST_CASE("[StreamPeerBuffer] Duplicate") {
+	uint8_t first = 5;
+	uint8_t second = 7;
+	uint8_t third = 11;
+
+	Ref<StreamPeerBuffer> spb;
+	spb.instantiate();
+	spb->put_u8(first);
+	spb->put_u8(second);
+	spb->put_u8(third);
+
+	Ref<StreamPeerBuffer> spb2 = spb->duplicate();
+
+	CHECK_EQ(spb2->get_u8(), first);
+	CHECK_EQ(spb2->get_u8(), second);
+	CHECK_EQ(spb2->get_u8(), third);
+}
+
+TEST_CASE("[StreamPeerBuffer] Put data with size equal to zero does nothing") {
+	Ref<StreamPeerBuffer> spb;
+	spb.instantiate();
+	uint8_t data = 42;
+
+	Error error = spb->put_data((const uint8_t *)&data, 0);
+
+	CHECK_EQ(error, OK);
+	CHECK_EQ(spb->get_size(), 0);
+	CHECK_EQ(spb->get_position(), 0);
+	CHECK_EQ(spb->get_available_bytes(), 0);
+}
+
+TEST_CASE("[StreamPeerBuffer] Get data with invalid size returns an error") {
+	Ref<StreamPeerBuffer> spb;
+	spb.instantiate();
+	uint8_t data = 42;
+	spb->put_u8(data);
+	spb->seek(0);
+
+	uint8_t data_out = 0;
+	Error error = spb->get_data(&data_out, 3);
+
+	CHECK_EQ(error, ERR_INVALID_PARAMETER);
+	CHECK_EQ(spb->get_size(), 1);
+	CHECK_EQ(spb->get_position(), 1);
+}
+
+} // namespace TestStreamPeerBuffer
+
+#endif // TEST_STREAM_PEER_BUFFER_H
diff --git a/tests/test_main.cpp b/tests/test_main.cpp
index 12ff3ad4bc9..9645df0ae69 100644
--- a/tests/test_main.cpp
+++ b/tests/test_main.cpp
@@ -52,6 +52,8 @@
 #include "tests/core/io/test_marshalls.h"
 #include "tests/core/io/test_pck_packer.h"
 #include "tests/core/io/test_resource.h"
+#include "tests/core/io/test_stream_peer.h"
+#include "tests/core/io/test_stream_peer_buffer.h"
 #include "tests/core/io/test_xml_parser.h"
 #include "tests/core/math/test_aabb.h"
 #include "tests/core/math/test_astar.h"