diff --git a/tests/layer_lock/config.h b/tests/layer_lock/config.h
new file mode 100644
index 00000000000..25d0b20c0ea
--- /dev/null
+++ b/tests/layer_lock/config.h
@@ -0,0 +1,8 @@
+// Copyright 2021 Christopher Courtney, aka Drashna Jael're  (@drashna) <drashna@live.com>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include "test_common.h"
+
+#define LAYER_LOCK_IDLE_TIMEOUT 1000
diff --git a/tests/layer_lock/test.mk b/tests/layer_lock/test.mk
new file mode 100644
index 00000000000..05771e4dbf8
--- /dev/null
+++ b/tests/layer_lock/test.mk
@@ -0,0 +1,8 @@
+# Copyright 2021 Christopher Courtney, aka Drashna Jael're  (@drashna) <drashna@live.com>
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+# --------------------------------------------------------------------------------
+# Keep this file, even if it is empty, as a marker that this folder contains tests
+# --------------------------------------------------------------------------------
+
+LAYER_LOCK_ENABLE = yes
diff --git a/tests/layer_lock/test_layer_lock.cpp b/tests/layer_lock/test_layer_lock.cpp
new file mode 100644
index 00000000000..76185fdb2d7
--- /dev/null
+++ b/tests/layer_lock/test_layer_lock.cpp
@@ -0,0 +1,148 @@
+// Copyright 2021 Christopher Courtney, aka Drashna Jael're  (@drashna) <drashna@live.com>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "keycodes.h"
+#include "test_common.hpp"
+
+using testing::_;
+
+class LayerLock : public TestFixture {};
+
+TEST_F(LayerLock, LayerLockMomentaryTest) {
+    TestDriver driver;
+    KeymapKey  key_layer = KeymapKey(0, 0, 0, MO(1));
+    KeymapKey  key_a     = KeymapKey(0, 1, 0, KC_A);
+    KeymapKey  key_trns  = KeymapKey(1, 0, 0, KC_TRNS);
+    KeymapKey  key_ll    = KeymapKey(1, 1, 0, QK_LAYER_LOCK);
+
+    set_keymap({key_layer, key_a, key_trns, key_ll});
+
+    /* Press Lower. */
+    EXPECT_NO_REPORT(driver);
+    key_layer.press();
+    run_one_scan_loop();
+    EXPECT_TRUE(layer_state_is(1));
+    VERIFY_AND_CLEAR(driver);
+
+    EXPECT_NO_REPORT(driver);
+    tap_key(key_ll);
+    EXPECT_TRUE(layer_state_is(1));
+    VERIFY_AND_CLEAR(driver);
+
+    EXPECT_NO_REPORT(driver);
+    key_layer.release();
+    run_one_scan_loop();
+    EXPECT_TRUE(layer_state_is(1));
+    VERIFY_AND_CLEAR(driver);
+}
+
+TEST_F(LayerLock, LayerLockLayerTapTest) {
+    TestDriver driver;
+    KeymapKey  key_layer = KeymapKey(0, 0, 0, LT(1, KC_B));
+    KeymapKey  key_a     = KeymapKey(0, 1, 0, KC_A);
+    KeymapKey  key_trns  = KeymapKey(1, 0, 0, KC_TRNS);
+    KeymapKey  key_ll    = KeymapKey(1, 1, 0, QK_LAYER_LOCK);
+
+    set_keymap({key_layer, key_a, key_trns, key_ll});
+
+    /* Press Lower. */
+    EXPECT_NO_REPORT(driver);
+    key_layer.press();
+    idle_for(TAPPING_TERM);
+    run_one_scan_loop();
+    EXPECT_TRUE(layer_state_is(1));
+    VERIFY_AND_CLEAR(driver);
+
+    EXPECT_NO_REPORT(driver);
+    tap_key(key_ll);
+    EXPECT_TRUE(layer_state_is(1));
+    VERIFY_AND_CLEAR(driver);
+}
+
+TEST_F(LayerLock, LayerLockOneshotTapTest) {
+    TestDriver driver;
+    KeymapKey  key_layer = KeymapKey(0, 0, 0, OSL(1));
+    KeymapKey  key_a     = KeymapKey(0, 1, 0, KC_A);
+    KeymapKey  key_trns  = KeymapKey(1, 0, 0, KC_TRNS);
+    KeymapKey  key_ll    = KeymapKey(1, 1, 0, QK_LAYER_LOCK);
+
+    set_keymap({key_layer, key_a, key_trns, key_ll});
+
+    /* Press Lower. */
+    EXPECT_NO_REPORT(driver);
+    tap_key(key_layer);
+    run_one_scan_loop();
+    EXPECT_TRUE(layer_state_is(1));
+    VERIFY_AND_CLEAR(driver);
+
+    EXPECT_NO_REPORT(driver);
+    tap_key(key_ll);
+    run_one_scan_loop();
+    EXPECT_TRUE(layer_state_is(1));
+    VERIFY_AND_CLEAR(driver);
+}
+
+TEST_F(LayerLock, LayerLockOneshotHoldTest) {
+    TestDriver driver;
+    KeymapKey  key_layer = KeymapKey(0, 0, 0, OSL(1));
+    KeymapKey  key_a     = KeymapKey(0, 1, 0, KC_A);
+    KeymapKey  key_trns  = KeymapKey(1, 0, 0, KC_TRNS);
+    KeymapKey  key_ll    = KeymapKey(1, 1, 0, QK_LAYER_LOCK);
+
+    set_keymap({key_layer, key_a, key_trns, key_ll});
+
+    /* Press Lower. */
+    EXPECT_NO_REPORT(driver);
+    key_layer.press();
+    idle_for(TAPPING_TERM);
+    run_one_scan_loop();
+    EXPECT_TRUE(layer_state_is(1));
+    VERIFY_AND_CLEAR(driver);
+
+    EXPECT_NO_REPORT(driver);
+    tap_key(key_ll);
+    run_one_scan_loop();
+    EXPECT_TRUE(layer_state_is(1));
+    VERIFY_AND_CLEAR(driver);
+
+    EXPECT_NO_REPORT(driver);
+    key_layer.release();
+    run_one_scan_loop();
+    EXPECT_TRUE(layer_state_is(1));
+    VERIFY_AND_CLEAR(driver);
+}
+
+
+TEST_F(LayerLock, LayerLockTimeoutTest) {
+    TestDriver driver;
+    KeymapKey  key_layer = KeymapKey(0, 0, 0, MO(1));
+    KeymapKey  key_a     = KeymapKey(0, 1, 0, KC_A);
+    KeymapKey  key_trns  = KeymapKey(1, 0, 0, KC_TRNS);
+    KeymapKey  key_ll    = KeymapKey(1, 1, 0, QK_LAYER_LOCK);
+
+    set_keymap({key_layer, key_a, key_trns, key_ll});
+
+    /* Press Lower. */
+    EXPECT_NO_REPORT(driver);
+    key_layer.press();
+    run_one_scan_loop();
+    EXPECT_TRUE(layer_state_is(1));
+    VERIFY_AND_CLEAR(driver);
+
+    EXPECT_NO_REPORT(driver);
+    tap_key(key_ll);
+    EXPECT_TRUE(layer_state_is(1));
+    VERIFY_AND_CLEAR(driver);
+
+    EXPECT_NO_REPORT(driver);
+    key_layer.release();
+    run_one_scan_loop();
+    EXPECT_TRUE(layer_state_is(1));
+    VERIFY_AND_CLEAR(driver);
+
+    EXPECT_NO_REPORT(driver);
+    idle_for(LAYER_LOCK_IDLE_TIMEOUT);
+    run_one_scan_loop();
+    EXPECT_FALSE(layer_state_is(1));
+    VERIFY_AND_CLEAR(driver);
+}