qmk_firmware/tests/tap_hold_configurations/flow_tap/test_tap_hold.cpp

// Copyright 2025 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "keyboard_report_util.hpp"
#include "keycode.h"
#include "test_common.hpp"
#include "action_tapping.h"
#include "test_fixture.hpp"
#include "test_keymap_key.hpp"

using testing::_;
using testing::AnyNumber;
using testing::InSequence;

class FlowTapTest : public TestFixture {};

// Test an input of quick distinct taps. All should be settled as tapped.
TEST_F(FlowTapTest, distinct_taps) {
    TestDriver driver;
    InSequence s;
    auto       regular_key  = KeymapKey(0, 0, 0, KC_A);
    auto       mod_tap_key1 = KeymapKey(0, 1, 0, SFT_T(KC_B));
    auto       mod_tap_key2 = KeymapKey(0, 2, 0, CTL_T(KC_C));
    auto       mod_tap_key3 = KeymapKey(0, 3, 0, ALT_T(KC_D));

    set_keymap({regular_key, mod_tap_key1, mod_tap_key2, mod_tap_key3});

    // Tap regular key.
    EXPECT_REPORT(driver, (KC_A));
    EXPECT_EMPTY_REPORT(driver);
    tap_key(regular_key, FLOW_TAP_TERM + 1);
    VERIFY_AND_CLEAR(driver);

    // Tap mod-tap 1.
    EXPECT_REPORT(driver, (KC_B));
    mod_tap_key1.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    EXPECT_EMPTY_REPORT(driver);
    idle_for(FLOW_TAP_TERM + 1);
    mod_tap_key1.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    // Tap mod-tap 2.
    EXPECT_REPORT(driver, (KC_C));
    mod_tap_key2.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    EXPECT_EMPTY_REPORT(driver);
    idle_for(FLOW_TAP_TERM + 1);
    mod_tap_key2.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    // Tap mod-tap 3.
    EXPECT_REPORT(driver, (KC_D));
    mod_tap_key3.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    EXPECT_EMPTY_REPORT(driver);
    idle_for(FLOW_TAP_TERM + 1);
    mod_tap_key3.release();
    idle_for(FLOW_TAP_TERM + 1); // Pause between taps.
    VERIFY_AND_CLEAR(driver);

    // Tap mod-tap 1.
    EXPECT_NO_REPORT(driver);
    mod_tap_key1.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    EXPECT_REPORT(driver, (KC_B));
    EXPECT_EMPTY_REPORT(driver);
    idle_for(FLOW_TAP_TERM + 1);
    mod_tap_key1.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    // Tap mod-tap 2.
    EXPECT_REPORT(driver, (KC_C));
    mod_tap_key2.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    EXPECT_EMPTY_REPORT(driver);
    idle_for(TAPPING_TERM + 1);
    mod_tap_key2.release();
    idle_for(FLOW_TAP_TERM + 1);
    VERIFY_AND_CLEAR(driver);
}

// By default, Flow Tap is disabled when mods other than Shift and AltGr are on.
TEST_F(FlowTapTest, hotkey_taps) {
    TestDriver driver;
    InSequence s;
    auto       ctrl_key    = KeymapKey(0, 0, 0, KC_LCTL);
    auto       shft_key    = KeymapKey(0, 1, 0, KC_LSFT);
    auto       alt_key     = KeymapKey(0, 2, 0, KC_LALT);
    auto       gui_key     = KeymapKey(0, 3, 0, KC_LGUI);
    auto       regular_key = KeymapKey(0, 4, 0, KC_A);
    auto       mod_tap_key = KeymapKey(0, 5, 0, RCTL_T(KC_B));

    set_keymap({ctrl_key, shft_key, alt_key, gui_key, regular_key, mod_tap_key});

    for (KeymapKey* mod_key : {&ctrl_key, &alt_key, &gui_key}) {
        // Hold mod key.
        EXPECT_REPORT(driver, (mod_key->code));
        mod_key->press();
        run_one_scan_loop();

        // Tap regular key.
        EXPECT_REPORT(driver, (mod_key->code, KC_A));
        regular_key.press();
        run_one_scan_loop();
        VERIFY_AND_CLEAR(driver);

        EXPECT_REPORT(driver, (mod_key->code));
        regular_key.release();
        run_one_scan_loop();
        VERIFY_AND_CLEAR(driver);

        // Press mod-tap, where Flow Tap is disabled due to the held mod.
        EXPECT_REPORT(driver, (mod_key->code, KC_RCTL));
        mod_tap_key.press();
        idle_for(TAPPING_TERM + 1);
        VERIFY_AND_CLEAR(driver);

        // Release mod-tap.
        EXPECT_REPORT(driver, (mod_key->code));
        mod_tap_key.release();
        run_one_scan_loop();

        // Release mod key.
        EXPECT_EMPTY_REPORT(driver);
        mod_key->release();
        run_one_scan_loop();
        VERIFY_AND_CLEAR(driver);
    }

    // Hold Shift key.
    EXPECT_REPORT(driver, (KC_LSFT));
    shft_key.press();
    run_one_scan_loop();

    // Tap regular key.
    EXPECT_REPORT(driver, (KC_LSFT, KC_A));
    regular_key.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    EXPECT_REPORT(driver, (KC_LSFT));
    regular_key.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    // Press mod-tap, where Flow Tap applies to settle as tapped.
    EXPECT_REPORT(driver, (KC_LSFT, KC_B));
    mod_tap_key.press();
    idle_for(TAPPING_TERM + 1);
    VERIFY_AND_CLEAR(driver);

    // Release mod-tap.
    EXPECT_REPORT(driver, (KC_LSFT));
    mod_tap_key.release();
    run_one_scan_loop();

    // Release Shift key.
    EXPECT_EMPTY_REPORT(driver);
    shft_key.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);
}

// Test input with two mod-taps in a rolled press quickly after a regular key.
TEST_F(FlowTapTest, rolled_press) {
    TestDriver driver;
    InSequence s;
    auto       regular_key  = KeymapKey(0, 0, 0, KC_A);
    auto       mod_tap_key1 = KeymapKey(0, 1, 0, SFT_T(KC_B));
    auto       mod_tap_key2 = KeymapKey(0, 2, 0, CTL_T(KC_C));

    set_keymap({regular_key, mod_tap_key1, mod_tap_key2});

    // Tap regular key.
    EXPECT_REPORT(driver, (KC_A));
    EXPECT_EMPTY_REPORT(driver);
    tap_key(regular_key);
    VERIFY_AND_CLEAR(driver);

    // Press mod-tap key 1 quickly after regular key. The mod-tap should settle
    // immediately as tapped, sending `KC_B`.
    EXPECT_REPORT(driver, (KC_B));
    mod_tap_key1.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    // Press mod-tap key 2 quickly.
    EXPECT_REPORT(driver, (KC_B, KC_C));
    mod_tap_key2.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    // Hold for longer than the tapping term.
    EXPECT_NO_REPORT(driver);
    idle_for(TAPPING_TERM + 1);
    VERIFY_AND_CLEAR(driver);

    // Release mod-tap keys.
    EXPECT_REPORT(driver, (KC_C));
    EXPECT_EMPTY_REPORT(driver);
    mod_tap_key1.release();
    run_one_scan_loop();
    mod_tap_key2.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);
}

TEST_F(FlowTapTest, long_flow_tap_settled_as_held) {
    TestDriver driver;
    InSequence s;
    auto       regular_key = KeymapKey(0, 0, 0, KC_A);
    auto       mod_tap_key = KeymapKey(0, 1, 0, SFT_T(KC_B));

    set_keymap({regular_key, mod_tap_key});

    // Tap regular key.
    EXPECT_REPORT(driver, (KC_A));
    EXPECT_EMPTY_REPORT(driver);
    tap_key(regular_key);
    VERIFY_AND_CLEAR(driver);

    EXPECT_NO_REPORT(driver);
    idle_for(FLOW_TAP_TERM + 1);
    VERIFY_AND_CLEAR(driver);

    // Press mod-tap key.
    EXPECT_NO_REPORT(driver);
    mod_tap_key.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    // Hold for the tapping term.
    EXPECT_REPORT(driver, (KC_LSFT));
    idle_for(TAPPING_TERM);
    VERIFY_AND_CLEAR(driver);

    // Release mod-tap key.
    EXPECT_EMPTY_REPORT(driver);
    mod_tap_key.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);
}

TEST_F(FlowTapTest, holding_multiple_mod_taps) {
    TestDriver driver;
    InSequence s;
    auto       regular_key  = KeymapKey(0, 0, 0, KC_A);
    auto       mod_tap_key1 = KeymapKey(0, 1, 0, SFT_T(KC_B));
    auto       mod_tap_key2 = KeymapKey(0, 2, 0, CTL_T(KC_C));

    set_keymap({regular_key, mod_tap_key1, mod_tap_key2});

    // Tap regular key.
    EXPECT_REPORT(driver, (KC_A));
    EXPECT_EMPTY_REPORT(driver);
    tap_key(regular_key);
    VERIFY_AND_CLEAR(driver);

    EXPECT_NO_REPORT(driver);
    idle_for(FLOW_TAP_TERM + 1);
    VERIFY_AND_CLEAR(driver);

    // Press mod-tap keys.
    EXPECT_NO_REPORT(driver);
    mod_tap_key1.press();
    run_one_scan_loop();
    mod_tap_key2.press();
    idle_for(TAPPING_TERM - 5); // Hold almost until tapping term.
    VERIFY_AND_CLEAR(driver);

    // Press regular key.
    EXPECT_REPORT(driver, (KC_LSFT));
    EXPECT_REPORT(driver, (KC_LSFT, KC_LCTL));
    EXPECT_REPORT(driver, (KC_LSFT, KC_LCTL, KC_A));
    regular_key.press();
    idle_for(10);
    VERIFY_AND_CLEAR(driver);

    // Release keys.
    EXPECT_REPORT(driver, (KC_LSFT, KC_LCTL));
    EXPECT_REPORT(driver, (KC_LCTL));
    EXPECT_EMPTY_REPORT(driver);
    regular_key.release();
    run_one_scan_loop();
    mod_tap_key1.release();
    run_one_scan_loop();
    mod_tap_key2.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);
}

TEST_F(FlowTapTest, holding_mod_tap_with_regular_mod) {
    TestDriver driver;
    InSequence s;
    auto       regular_key = KeymapKey(0, 0, 0, KC_A);
    auto       mod_key     = KeymapKey(0, 1, 0, KC_LSFT);
    auto       mod_tap_key = KeymapKey(0, 2, 0, CTL_T(KC_C));

    set_keymap({regular_key, mod_key, mod_tap_key});

    // Tap regular key.
    EXPECT_REPORT(driver, (KC_A));
    EXPECT_EMPTY_REPORT(driver);
    tap_key(regular_key);
    VERIFY_AND_CLEAR(driver);

    EXPECT_NO_REPORT(driver);
    idle_for(FLOW_TAP_TERM + 1);
    VERIFY_AND_CLEAR(driver);

    // Press mod and mod-tap keys.
    EXPECT_REPORT(driver, (KC_LSFT));
    mod_key.press();
    run_one_scan_loop();
    mod_tap_key.press();
    idle_for(TAPPING_TERM - 5); // Hold almost until tapping term.
    VERIFY_AND_CLEAR(driver);

    // Press regular key.
    EXPECT_REPORT(driver, (KC_LSFT, KC_LCTL));
    EXPECT_REPORT(driver, (KC_LSFT, KC_LCTL, KC_A));
    regular_key.press();
    idle_for(10);
    VERIFY_AND_CLEAR(driver);

    // Release keys.
    EXPECT_REPORT(driver, (KC_LSFT, KC_LCTL));
    EXPECT_REPORT(driver, (KC_LCTL));
    EXPECT_EMPTY_REPORT(driver);
    regular_key.release();
    run_one_scan_loop();
    mod_key.release();
    run_one_scan_loop();
    mod_tap_key.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);
}

TEST_F(FlowTapTest, layer_tap_key) {
    TestDriver driver;
    InSequence s;
    auto       regular_key   = KeymapKey(0, 0, 0, KC_A);
    auto       layer_tap_key = KeymapKey(0, 1, 0, LT(1, KC_B));
    auto       regular_key2  = KeymapKey(1, 0, 0, KC_C);

    set_keymap({regular_key, layer_tap_key, regular_key2});

    // Tap regular key.
    EXPECT_REPORT(driver, (KC_A));
    EXPECT_EMPTY_REPORT(driver);
    tap_key(regular_key);
    VERIFY_AND_CLEAR(driver);

    // Press layer-tap key, quickly after the regular key.
    EXPECT_REPORT(driver, (KC_B));
    layer_tap_key.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    EXPECT_NO_REPORT(driver);
    idle_for(TAPPING_TERM + 1);
    VERIFY_AND_CLEAR(driver);

    // Release layer-tap key.
    EXPECT_EMPTY_REPORT(driver);
    layer_tap_key.release();
    run_one_scan_loop();

    // Tap regular key.
    EXPECT_REPORT(driver, (KC_A));
    EXPECT_EMPTY_REPORT(driver);
    tap_key(regular_key);
    VERIFY_AND_CLEAR(driver);

    EXPECT_NO_REPORT(driver);
    idle_for(FLOW_TAP_TERM + 1);
    VERIFY_AND_CLEAR(driver);

    // Press layer-tap key, slowly after the regular key.
    EXPECT_NO_REPORT(driver);
    layer_tap_key.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    EXPECT_NO_REPORT(driver);
    idle_for(TAPPING_TERM + 1);
    EXPECT_EQ(layer_state, 1 << 1);
    VERIFY_AND_CLEAR(driver);

    // Tap regular key2.
    EXPECT_REPORT(driver, (KC_C));
    EXPECT_EMPTY_REPORT(driver);
    tap_key(regular_key);
    VERIFY_AND_CLEAR(driver);

    // Release layer-tap key.
    EXPECT_NO_REPORT(driver);
    layer_tap_key.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);
}

TEST_F(FlowTapTest, layer_tap_ignored_with_disabled_key) {
    TestDriver driver;
    InSequence s;
    auto       no_key        = KeymapKey(0, 0, 0, KC_NO);
    auto       regular_key   = KeymapKey(1, 0, 0, KC_ESC);
    auto       layer_tap_key = KeymapKey(0, 1, 0, LT(1, KC_A));
    auto       mod_tap_key   = KeymapKey(0, 2, 0, CTL_T(KC_B));

    set_keymap({no_key, regular_key, layer_tap_key, mod_tap_key});

    EXPECT_REPORT(driver, (KC_ESC));
    EXPECT_EMPTY_REPORT(driver);
    layer_tap_key.press();
    idle_for(TAPPING_TERM + 1);
    tap_key(regular_key);
    layer_tap_key.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    EXPECT_REPORT(driver, (KC_LCTL));
    mod_tap_key.press();
    idle_for(TAPPING_TERM + 1);
    VERIFY_AND_CLEAR(driver);

    EXPECT_EMPTY_REPORT(driver);
    mod_tap_key.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);
}

TEST_F(FlowTapTest, layer_tap_ignored_with_disabled_key_complex) {
    TestDriver driver;
    InSequence s;
    auto       regular_key1  = KeymapKey(0, 0, 0, KC_Q);
    auto       layer_tap_key = KeymapKey(0, 1, 0, LT(1, KC_SPC));
    auto       mod_tap_key1  = KeymapKey(0, 2, 0, CTL_T(KC_T));
    // Place RALT_T(KC_I), where Flow Tap is enabled, in the same position on
    // layer 0 as KC_RGHT, where Flow Tap is disabled. This tests that Flow Tap
    // tracks the keycode from the correct layer.
    auto mod_tap_key2 = KeymapKey(0, 3, 0, RALT_T(KC_I));
    auto regular_key2 = KeymapKey(1, 3, 0, KC_RGHT);

    set_keymap({regular_key1, layer_tap_key, mod_tap_key1, mod_tap_key2, regular_key2});

    // Tap regular key 1.
    EXPECT_REPORT(driver, (KC_Q));
    EXPECT_EMPTY_REPORT(driver);
    tap_key(regular_key1);
    idle_for(FLOW_TAP_TERM + 1);
    VERIFY_AND_CLEAR(driver);

    // Hold layer-tap key.
    EXPECT_NO_REPORT(driver);
    layer_tap_key.press();
    run_one_scan_loop();
    // idle_for(TAPPING_TERM + 1);
    VERIFY_AND_CLEAR(driver);

    // Tap regular key 2.
    EXPECT_REPORT(driver, (KC_RGHT));
    EXPECT_EMPTY_REPORT(driver);
    tap_key(regular_key2);
    VERIFY_AND_CLEAR(driver);

    // Release layer-tap key.
    EXPECT_NO_REPORT(driver);
    layer_tap_key.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    // Quickly hold mod-tap key 1.
    EXPECT_NO_REPORT(driver);
    mod_tap_key1.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    EXPECT_REPORT(driver, (KC_LCTL));
    EXPECT_REPORT(driver, (KC_LCTL, KC_Q));
    EXPECT_REPORT(driver, (KC_LCTL));
    tap_key(regular_key1);
    VERIFY_AND_CLEAR(driver);

    EXPECT_EMPTY_REPORT(driver);
    mod_tap_key1.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);
}

TEST_F(FlowTapTest, layer_tap_ignored_with_enabled_key) {
    TestDriver driver;
    InSequence s;
    auto       no_key        = KeymapKey(0, 0, 0, KC_NO);
    auto       regular_key   = KeymapKey(1, 0, 0, KC_C);
    auto       layer_tap_key = KeymapKey(0, 1, 0, LT(1, KC_A));
    auto       mod_tap_key   = KeymapKey(0, 2, 0, CTL_T(KC_B));

    set_keymap({no_key, regular_key, layer_tap_key, mod_tap_key});

    EXPECT_REPORT(driver, (KC_C));
    EXPECT_EMPTY_REPORT(driver);
    layer_tap_key.press();
    idle_for(TAPPING_TERM + 1);
    tap_key(regular_key);
    layer_tap_key.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    EXPECT_REPORT(driver, (KC_B));
    mod_tap_key.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    EXPECT_EMPTY_REPORT(driver);
    idle_for(TAPPING_TERM + 1);
    mod_tap_key.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);
}

TEST_F(FlowTapTest, combo_key) {
    TestDriver driver;
    InSequence s;
    auto       regular_key   = KeymapKey(0, 0, 0, KC_A);
    auto       mod_tap_key   = KeymapKey(0, 1, 0, SFT_T(KC_X));
    auto       layer_tap_key = KeymapKey(0, 2, 0, LT(1, KC_Y));

    set_keymap({regular_key, mod_tap_key, layer_tap_key});

    // Tap regular key.
    EXPECT_REPORT(driver, (KC_A));
    EXPECT_EMPTY_REPORT(driver);
    tap_key(regular_key);
    VERIFY_AND_CLEAR(driver);

    // Press combo keys quickly after regular key.
    EXPECT_REPORT(driver, (KC_Z));
    EXPECT_EMPTY_REPORT(driver);
    tap_combo({mod_tap_key, layer_tap_key});
    VERIFY_AND_CLEAR(driver);

    // Press mod-tap key quickly.
    EXPECT_REPORT(driver, (KC_X));
    mod_tap_key.press();
    idle_for(TAPPING_TERM + 1);
    VERIFY_AND_CLEAR(driver);

    // Release mod-tap key.
    EXPECT_EMPTY_REPORT(driver);
    mod_tap_key.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);
}

TEST_F(FlowTapTest, oneshot_mod_key) {
    TestDriver driver;
    InSequence s;
    auto       regular_key = KeymapKey(0, 0, 0, KC_A);
    auto       osm_key     = KeymapKey(0, 1, 0, OSM(MOD_LSFT));

    set_keymap({regular_key, osm_key});

    // Tap regular key.
    EXPECT_REPORT(driver, (KC_A));
    EXPECT_EMPTY_REPORT(driver);
    tap_key(regular_key);
    VERIFY_AND_CLEAR(driver);

    // Tap OSM, tap regular key.
    EXPECT_CALL(driver, send_keyboard_mock(KeyboardReport(KC_LSFT))).Times(AnyNumber());
    EXPECT_REPORT(driver, (KC_LSFT, KC_A));
    EXPECT_EMPTY_REPORT(driver);
    tap_key(osm_key);
    tap_key(regular_key);
    VERIFY_AND_CLEAR(driver);

    // Nested press of OSM and regular keys.
    EXPECT_CALL(driver, send_keyboard_mock(KeyboardReport(KC_LSFT))).Times(AnyNumber());
    EXPECT_REPORT(driver, (KC_LSFT, KC_A));
    EXPECT_CALL(driver, send_keyboard_mock(KeyboardReport(KC_LSFT))).Times(AnyNumber());
    EXPECT_EMPTY_REPORT(driver);
    osm_key.press();
    run_one_scan_loop();
    tap_key(regular_key);
    osm_key.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);
}

TEST_F(FlowTapTest, quick_tap) {
    TestDriver driver;
    InSequence s;
    auto       mod_tap_key = KeymapKey(0, 1, 0, SFT_T(KC_A));

    set_keymap({mod_tap_key});

    EXPECT_REPORT(driver, (KC_A));
    EXPECT_EMPTY_REPORT(driver);
    tap_key(mod_tap_key);
    VERIFY_AND_CLEAR(driver);

    EXPECT_REPORT(driver, (KC_A));
    mod_tap_key.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    EXPECT_NO_REPORT(driver);
    idle_for(TAPPING_TERM + 1);
    VERIFY_AND_CLEAR(driver);

    // Release mod-tap key.
    EXPECT_EMPTY_REPORT(driver);
    mod_tap_key.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);
}

TEST_F(FlowTapTest, rolling_mt_mt) {
    TestDriver driver;
    InSequence s;
    auto       mod_tap_key1 = KeymapKey(0, 1, 0, SFT_T(KC_A));
    auto       mod_tap_key2 = KeymapKey(0, 2, 0, CTL_T(KC_B));

    set_keymap({mod_tap_key1, mod_tap_key2});

    EXPECT_NO_REPORT(driver);
    idle_for(FLOW_TAP_TERM + 1);
    mod_tap_key1.press();
    run_one_scan_loop();
    mod_tap_key2.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    EXPECT_REPORT(driver, (KC_A));
    EXPECT_REPORT(driver, (KC_A, KC_B));
    EXPECT_REPORT(driver, (KC_B));
    mod_tap_key1.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    // Hold for longer than the tapping term.
    EXPECT_NO_REPORT(driver);
    idle_for(TAPPING_TERM + 1);
    VERIFY_AND_CLEAR(driver);

    // Release mod-tap keys.
    EXPECT_EMPTY_REPORT(driver);
    mod_tap_key2.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);
}

TEST_F(FlowTapTest, rolling_lt_mt_regular) {
    TestDriver driver;
    InSequence s;
    auto       layer_tap_key = KeymapKey(0, 0, 0, LT(1, KC_A));
    auto       mod_tap_key   = KeymapKey(0, 1, 0, CTL_T(KC_B));
    auto       regular_key   = KeymapKey(0, 2, 0, KC_C);

    set_keymap({layer_tap_key, mod_tap_key, regular_key});

    EXPECT_NO_REPORT(driver);
    idle_for(FLOW_TAP_TERM + 1);
    layer_tap_key.press();
    run_one_scan_loop();
    mod_tap_key.press();
    run_one_scan_loop();
    regular_key.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    EXPECT_REPORT(driver, (KC_A));
    EXPECT_REPORT(driver, (KC_A, KC_B));
    EXPECT_REPORT(driver, (KC_A, KC_B, KC_C));
    EXPECT_REPORT(driver, (KC_B, KC_C));
    layer_tap_key.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    // Hold for longer than the tapping term.
    EXPECT_NO_REPORT(driver);
    idle_for(TAPPING_TERM + 1);
    VERIFY_AND_CLEAR(driver);

    // Release mod-tap keys.
    EXPECT_REPORT(driver, (KC_C));
    EXPECT_EMPTY_REPORT(driver);
    mod_tap_key.release();
    run_one_scan_loop();
    regular_key.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);
}

TEST_F(FlowTapTest, rolling_lt_regular_mt) {
    TestDriver driver;
    InSequence s;
    auto       layer_tap_key = KeymapKey(0, 0, 0, LT(1, KC_A));
    auto       regular_key   = KeymapKey(0, 1, 0, KC_B);
    auto       mod_tap_key   = KeymapKey(0, 2, 0, CTL_T(KC_C));

    set_keymap({layer_tap_key, regular_key, mod_tap_key});

    EXPECT_NO_REPORT(driver);
    idle_for(FLOW_TAP_TERM + 1);
    layer_tap_key.press();
    run_one_scan_loop();
    regular_key.press();
    run_one_scan_loop();
    mod_tap_key.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    EXPECT_REPORT(driver, (KC_A));
    EXPECT_REPORT(driver, (KC_A, KC_B));
    EXPECT_REPORT(driver, (KC_A, KC_B, KC_C));
    EXPECT_REPORT(driver, (KC_B, KC_C));
    layer_tap_key.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    // Hold for longer than the tapping term.
    EXPECT_NO_REPORT(driver);
    idle_for(TAPPING_TERM + 1);
    VERIFY_AND_CLEAR(driver);

    // Release mod-tap keys.
    EXPECT_REPORT(driver, (KC_C));
    EXPECT_EMPTY_REPORT(driver);
    regular_key.release();
    run_one_scan_loop();
    mod_tap_key.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);
}

TEST_F(FlowTapTest, rolling_mt_mt_mt) {
    TestDriver driver;
    InSequence s;
    auto       mod_tap_key1 = KeymapKey(0, 0, 0, CTL_T(KC_A));
    auto       mod_tap_key2 = KeymapKey(0, 1, 0, GUI_T(KC_B));
    auto       mod_tap_key3 = KeymapKey(0, 2, 0, ALT_T(KC_C));

    set_keymap({mod_tap_key1, mod_tap_key2, mod_tap_key3});

    // Press mod-tap keys.
    EXPECT_NO_REPORT(driver);
    idle_for(FLOW_TAP_TERM + 1);
    mod_tap_key1.press();
    run_one_scan_loop();
    mod_tap_key2.press();
    run_one_scan_loop();
    mod_tap_key3.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    // Release first mod-tap key.
    EXPECT_REPORT(driver, (KC_A));
    EXPECT_REPORT(driver, (KC_A, KC_B));
    EXPECT_REPORT(driver, (KC_A, KC_B, KC_C));
    EXPECT_REPORT(driver, (KC_B, KC_C));
    mod_tap_key1.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    // Hold for longer than the tapping term.
    EXPECT_NO_REPORT(driver);
    idle_for(TAPPING_TERM + 1);
    VERIFY_AND_CLEAR(driver);

    // Release other mod-tap keys.
    EXPECT_REPORT(driver, (KC_C));
    EXPECT_EMPTY_REPORT(driver);
    mod_tap_key2.release();
    run_one_scan_loop();
    mod_tap_key3.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);
}

TEST_F(FlowTapTest, roll_release_132) {
    TestDriver driver;
    InSequence s;
    auto       mod_tap_key1 = KeymapKey(0, 0, 0, CTL_T(KC_A));
    auto       mod_tap_key2 = KeymapKey(0, 1, 0, GUI_T(KC_B));
    auto       mod_tap_key3 = KeymapKey(0, 2, 0, ALT_T(KC_C));

    set_keymap({mod_tap_key1, mod_tap_key2, mod_tap_key3});

    // Press mod-tap keys.
    EXPECT_NO_REPORT(driver);
    idle_for(FLOW_TAP_TERM + 1);
    mod_tap_key1.press();
    run_one_scan_loop();
    mod_tap_key2.press();
    idle_for(FLOW_TAP_TERM + 1);
    mod_tap_key3.press();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    // Release first mod-tap key.
    EXPECT_REPORT(driver, (KC_A));
    EXPECT_REPORT(driver, (KC_A, KC_B));
    EXPECT_REPORT(driver, (KC_B));
    mod_tap_key1.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);

    // Release other mod-tap keys.
    EXPECT_REPORT(driver, (KC_B, KC_C));
    EXPECT_REPORT(driver, (KC_B));
    EXPECT_EMPTY_REPORT(driver);
    mod_tap_key3.release();
    run_one_scan_loop();
    mod_tap_key2.release();
    run_one_scan_loop();
    VERIFY_AND_CLEAR(driver);
}