7 files changed, 180 insertions, 3 deletions
diff --git a/quantum/encoder.c b/quantum/encoder.c
index 1393e34868..3aee340249 100644
--- a/quantum/encoder.c
+++ b/quantum/encoder.c
@@ -80,6 +80,10 @@ __attribute__((weak)) bool encoder_update_kb(uint8_t index, bool clockwise) {
     return encoder_update_user(index, clockwise);
 }
 
+__attribute__((weak)) bool should_process_encoder(void) {
+    return is_keyboard_master();
+}
+
 void encoder_init(void) {
 #ifdef SPLIT_KEYBOARD
     thisHand  = isLeftHand ? 0 : NUM_ENCODERS_LEFT;
@@ -179,8 +183,11 @@ static bool encoder_update(uint8_t index, uint8_t state) {
 
             encoder_value[index]++;
             changed = true;
+#ifdef SPLIT_KEYBOARD
+            if (should_process_encoder())
+#endif // SPLIT_KEYBOARD
 #ifdef ENCODER_MAP_ENABLE
-            encoder_exec_mapping(index, ENCODER_COUNTER_CLOCKWISE);
+                encoder_exec_mapping(index, ENCODER_COUNTER_CLOCKWISE);
 #else  // ENCODER_MAP_ENABLE
         encoder_update_kb(index, ENCODER_COUNTER_CLOCKWISE);
 #endif // ENCODER_MAP_ENABLE
@@ -193,8 +200,11 @@ static bool encoder_update(uint8_t index, uint8_t state) {
 #endif
             encoder_value[index]--;
             changed = true;
+#ifdef SPLIT_KEYBOARD
+            if (should_process_encoder())
+#endif // SPLIT_KEYBOARD
 #ifdef ENCODER_MAP_ENABLE
-            encoder_exec_mapping(index, ENCODER_CLOCKWISE);
+                encoder_exec_mapping(index, ENCODER_CLOCKWISE);
 #else  // ENCODER_MAP_ENABLE
         encoder_update_kb(index, ENCODER_CLOCKWISE);
 #endif // ENCODER_MAP_ENABLE
diff --git a/quantum/encoder/tests/config_mock_split_role.h b/quantum/encoder/tests/config_mock_split_role.h
new file mode 100644
index 0000000000..c80ac4d519
--- /dev/null
+++ b/quantum/encoder/tests/config_mock_split_role.h
@@ -0,0 +1,26 @@
+// Copyright 2022 Nick Brassel (@tzarc)
+// SPDX-License-Identifier: GPL-2.0-or-later
+#pragma once
+
+#define MATRIX_ROWS 1
+#define MATRIX_COLS 1
+
+/* Here, "pins" from 0 to 31 are allowed. */
+#define ENCODERS_PAD_A \
+    { 0, 2 }
+#define ENCODERS_PAD_B \
+    { 1, 3 }
+#define ENCODERS_PAD_A_RIGHT \
+    { 4, 6 }
+#define ENCODERS_PAD_B_RIGHT \
+    { 5, 7 }
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "mock_split.h"
+
+#ifdef __cplusplus
+};
+#endif
diff --git a/quantum/encoder/tests/encoder_tests_split_role.cpp b/quantum/encoder/tests/encoder_tests_split_role.cpp
new file mode 100644
index 0000000000..02264067f4
--- /dev/null
+++ b/quantum/encoder/tests/encoder_tests_split_role.cpp
@@ -0,0 +1,122 @@
+/* Copyright 2021 Balz Guenat
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "gtest/gtest.h"
+#include "gmock/gmock.h"
+#include <vector>
+#include <algorithm>
+#include <stdio.h>
+
+extern "C" {
+#include "encoder.h"
+#include "encoder/tests/mock_split.h"
+}
+
+struct update {
+    int8_t index;
+    bool   clockwise;
+};
+
+uint8_t num_updates = 0;
+
+bool isMaster;
+bool isLeftHand;
+
+bool is_keyboard_master(void) {
+    return isMaster;
+}
+
+bool encoder_update_kb(uint8_t index, bool clockwise) {
+    if (!isMaster) {
+        ADD_FAILURE() << "We shouldn't get here.";
+    }
+    num_updates++;
+    return true;
+}
+
+bool setAndRead(pin_t pin, bool val) {
+    setPin(pin, val);
+    return encoder_read();
+}
+
+class EncoderSplitTestRole : public ::testing::Test {
+   protected:
+    void SetUp() override {
+        num_updates = 0;
+        for (int i = 0; i < 32; i++) {
+            pinIsInputHigh[i] = 0;
+            pins[i]           = 0;
+        }
+    }
+};
+
+TEST_F(EncoderSplitTestRole, TestPrimaryLeft) {
+    isMaster   = true;
+    isLeftHand = true;
+    encoder_init();
+    // send 4 pulses. with resolution 4, that's one step and we should get 1 update.
+    setAndRead(0, false);
+    setAndRead(1, false);
+    setAndRead(0, true);
+    setAndRead(1, true);
+
+    EXPECT_EQ(num_updates, 1); // one update received
+}
+
+TEST_F(EncoderSplitTestRole, TestPrimaryRight) {
+    isMaster   = true;
+    isLeftHand = false;
+    encoder_init();
+    // send 4 pulses. with resolution 4, that's one step and we should get 1 update.
+    setAndRead(6, false);
+    setAndRead(7, false);
+    setAndRead(6, true);
+    setAndRead(7, true);
+
+    uint8_t slave_state[32] = {0};
+    encoder_state_raw(slave_state);
+
+    EXPECT_EQ(num_updates, 1); // one update received
+}
+
+TEST_F(EncoderSplitTestRole, TestNotPrimaryLeft) {
+    isMaster   = false;
+    isLeftHand = true;
+    encoder_init();
+    // send 4 pulses. with resolution 4, that's one step and we should get 1 update.
+    setAndRead(0, false);
+    setAndRead(1, false);
+    setAndRead(0, true);
+    setAndRead(1, true);
+
+    EXPECT_EQ(num_updates, 0); // zero updates received
+}
+
+TEST_F(EncoderSplitTestRole, TestNotPrimaryRight) {
+    isMaster   = false;
+    isLeftHand = false;
+    encoder_init();
+    // send 4 pulses. with resolution 4, that's one step and we should get 1 update.
+    setAndRead(6, false);
+    setAndRead(7, false);
+    setAndRead(6, true);
+    setAndRead(7, true);
+
+    uint8_t slave_state[32] = {0};
+    encoder_state_raw(slave_state);
+
+    EXPECT_EQ(num_updates, 0); // zero updates received
+}
diff --git a/quantum/encoder/tests/mock.c b/quantum/encoder/tests/mock.c
index 10a00cb8f2..61f2f8294d 100644
--- a/quantum/encoder/tests/mock.c
+++ b/quantum/encoder/tests/mock.c
@@ -34,3 +34,7 @@ bool setPin(pin_t pin, bool val) {
     pins[pin] = val;
     return val;
 }
+
+__attribute__((weak)) bool is_keyboard_master(void) {
+    return true;
+}
diff --git a/quantum/encoder/tests/mock_split.c b/quantum/encoder/tests/mock_split.c
index dd3c26d958..5cc6cd19e1 100644
--- a/quantum/encoder/tests/mock_split.c
+++ b/quantum/encoder/tests/mock_split.c
@@ -36,3 +36,7 @@ bool setPin(pin_t pin, bool val) {
 }
 
 void last_encoder_activity_trigger(void) {}
+
+__attribute__((weak)) bool is_keyboard_master(void) {
+    return true;
+}
diff --git a/quantum/encoder/tests/rules.mk b/quantum/encoder/tests/rules.mk
index 6a2611952c..d01c1c66ee 100644
--- a/quantum/encoder/tests/rules.mk
+++ b/quantum/encoder/tests/rules.mk
@@ -56,3 +56,13 @@ encoder_split_no_right_SRC := \
 	$(QUANTUM_PATH)/encoder/tests/mock_split.c \
 	$(QUANTUM_PATH)/encoder/tests/encoder_tests_split_no_right.cpp \
 	$(QUANTUM_PATH)/encoder.c
+
+encoder_split_role_DEFS := -DENCODER_TESTS -DENCODER_ENABLE -DENCODER_MOCK_SPLIT
+encoder_split_role_INC := $(QUANTUM_PATH)/split_common
+encoder_split_role_CONFIG := $(QUANTUM_PATH)/encoder/tests/config_mock_split_role.h
+
+encoder_split_role_SRC := \
+	platforms/test/timer.c \
+	$(QUANTUM_PATH)/encoder/tests/mock_split.c \
+	$(QUANTUM_PATH)/encoder/tests/encoder_tests_split_role.cpp \
+	$(QUANTUM_PATH)/encoder.c
diff --git a/quantum/encoder/tests/testlist.mk b/quantum/encoder/tests/testlist.mk
index 6b2fd84d96..a407f1fadd 100644
--- a/quantum/encoder/tests/testlist.mk
+++ b/quantum/encoder/tests/testlist.mk
@@ -4,4 +4,5 @@ TEST_LIST += \
 	encoder_split_left_gt_right \
 	encoder_split_left_lt_right \
 	encoder_split_no_left \
-	encoder_split_no_right
+	encoder_split_no_right \
+	encoder_split_role \