diff --git a/tests/plugins/CharShift/basic/basic.ino b/tests/plugins/CharShift/basic/basic.ino
new file mode 100644
index 00000000..05929f4e
--- /dev/null
+++ b/tests/plugins/CharShift/basic/basic.ino
@@ -0,0 +1,55 @@
+/* -*- mode: c++ -*-
+ * Copyright (C) 2021 Keyboard.io, Inc.
+ *
+ * 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, version 3.
+ *
+ * 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 .
+ */
+
+#include
+#include
+
+// *INDENT-OFF*
+KEYMAPS(
+ [0] = KEYMAP_STACKED
+ (
+ Key_LeftShift, Key_RightShift, ___, ___, ___, ___, ___,
+ Key_X, LSHIFT(Key_Y), ___, ___, ___, ___, ___,
+ CS(0), CS(1), CS(2), CS(3), ___, ___,
+ ___, ___, ___, ___, ___, ___, ___,
+ ___, ___, ___, ___,
+ ___,
+
+ ___, ___, ___, ___, ___, ___, ___,
+ ___, ___, ___, ___, ___, ___, ___,
+ ___, ___, ___, ___, ___, ___,
+ ___, ___, ___, ___, ___, ___, ___,
+ ___, ___, ___, ___,
+ ___
+ ),
+)
+// *INDENT-ON*
+
+KALEIDOSCOPE_INIT_PLUGINS(CharShift);
+
+void setup() {
+ Kaleidoscope.setup();
+ CS_KEYS(
+ kaleidoscope::plugin::CharShift::KeyPair(Key_A, Key_B),
+ kaleidoscope::plugin::CharShift::KeyPair(Key_C, LSHIFT(Key_D)),
+ kaleidoscope::plugin::CharShift::KeyPair(LSHIFT(Key_E), Key_F),
+ kaleidoscope::plugin::CharShift::KeyPair(LSHIFT(Key_G), LSHIFT(Key_H)),
+ );
+}
+
+void loop() {
+ Kaleidoscope.loop();
+}
diff --git a/tests/plugins/CharShift/basic/sketch.json b/tests/plugins/CharShift/basic/sketch.json
new file mode 100644
index 00000000..8cc86922
--- /dev/null
+++ b/tests/plugins/CharShift/basic/sketch.json
@@ -0,0 +1,6 @@
+{
+ "cpu": {
+ "fqbn": "keyboardio:virtual:model01",
+ "port": ""
+ }
+}
diff --git a/tests/plugins/CharShift/basic/test.ktest b/tests/plugins/CharShift/basic/test.ktest
new file mode 100644
index 00000000..d8088620
--- /dev/null
+++ b/tests/plugins/CharShift/basic/test.ktest
@@ -0,0 +1,212 @@
+VERSION 1
+
+KEYSWITCH LSHIFT 0 0
+KEYSWITCH RSHIFT 0 1
+KEYSWITCH x 1 0
+KEYSWITCH Y 1 1
+KEYSWITCH CS_ab 2 0
+KEYSWITCH CS_cD 2 1
+KEYSWITCH CS_Ef 2 2
+KEYSWITCH CS_GH 2 3
+
+# ==============================================================================
+NAME CharShift lower lower
+
+RUN 4 ms
+PRESS CS_ab
+RUN 1 cycle
+EXPECT keyboard-report Key_A # report: { 4 }
+
+RUN 4 ms
+RELEASE CS_ab
+RUN 1 cycle
+EXPECT keyboard-report empty
+
+RUN 4 ms
+PRESS LSHIFT
+RUN 1 cycle
+EXPECT keyboard-report Key_LeftShift # report: { e1 }
+
+RUN 4 ms
+PRESS CS_ab
+RUN 1 cycle
+EXPECT keyboard-report empty
+EXPECT keyboard-report Key_B # report: { 5 }
+
+RUN 4 ms
+RELEASE CS_ab
+RUN 1 cycle
+EXPECT keyboard-report empty
+EXPECT keyboard-report Key_LeftShift # report: { e1 }
+
+RUN 4 ms
+RELEASE LSHIFT
+RUN 1 cycle
+EXPECT keyboard-report empty
+
+RUN 5 ms
+
+# ==============================================================================
+NAME CharShift lower upper
+
+RUN 4 ms
+PRESS CS_cD
+RUN 1 cycle
+EXPECT keyboard-report Key_C # report: { 6 }
+
+RUN 4 ms
+RELEASE CS_cD
+RUN 1 cycle
+EXPECT keyboard-report empty
+
+RUN 4 ms
+PRESS LSHIFT
+RUN 1 cycle
+EXPECT keyboard-report Key_LeftShift # report: { e1 }
+
+RUN 4 ms
+PRESS CS_cD
+RUN 1 cycle
+EXPECT keyboard-report Key_LeftShift Key_D # report: { e1 7 }
+
+RUN 4 ms
+RELEASE CS_cD
+RUN 1 cycle
+EXPECT keyboard-report Key_LeftShift # report: { e1 }
+
+RUN 4 ms
+RELEASE LSHIFT
+RUN 1 cycle
+EXPECT keyboard-report empty
+
+RUN 5 ms
+
+# ==============================================================================
+NAME CharShift upper lower
+
+RUN 4 ms
+PRESS CS_Ef
+RUN 1 cycle
+EXPECT keyboard-report Key_LeftShift # report: { e1 }
+EXPECT keyboard-report Key_LeftShift Key_E # report: { e1 8 }
+
+RUN 4 ms
+RELEASE CS_Ef
+RUN 1 cycle
+EXPECT keyboard-report Key_LeftShift # report: { e1 }
+EXPECT keyboard-report empty
+
+RUN 4 ms
+PRESS LSHIFT
+RUN 1 cycle
+EXPECT keyboard-report Key_LeftShift # report: { e1 }
+
+RUN 4 ms
+PRESS CS_Ef
+RUN 1 cycle
+EXPECT keyboard-report empty
+EXPECT keyboard-report Key_F # report: { 9 }
+
+RUN 4 ms
+RELEASE CS_Ef
+RUN 1 cycle
+EXPECT keyboard-report empty
+EXPECT keyboard-report Key_LeftShift # report: { e1 }
+
+RUN 4 ms
+RELEASE LSHIFT
+RUN 1 cycle
+EXPECT keyboard-report empty
+
+RUN 5 ms
+
+# ==============================================================================
+NAME CharShift upper upper
+
+RUN 4 ms
+PRESS CS_GH
+RUN 1 cycle
+EXPECT keyboard-report Key_LeftShift # report: { e1 }
+EXPECT keyboard-report Key_LeftShift Key_G # report: { e1 10 }
+
+RUN 4 ms
+RELEASE CS_GH
+RUN 1 cycle
+EXPECT keyboard-report Key_LeftShift # report: { e1 }
+EXPECT keyboard-report empty
+
+RUN 4 ms
+PRESS LSHIFT
+RUN 1 cycle
+EXPECT keyboard-report Key_LeftShift # report: { e1 }
+
+RUN 4 ms
+PRESS CS_GH
+RUN 1 cycle
+EXPECT keyboard-report Key_LeftShift Key_H # report: { e1 11 }
+
+RUN 4 ms
+RELEASE CS_GH
+RUN 1 cycle
+EXPECT keyboard-report Key_LeftShift # report: { e1 }
+
+RUN 4 ms
+RELEASE LSHIFT
+RUN 1 cycle
+EXPECT keyboard-report empty
+
+RUN 5 ms
+
+# ==============================================================================
+NAME Rollover from normal to CharShift upper
+
+RUN 4 ms
+PRESS x
+RUN 1 cycle
+EXPECT keyboard-report Key_X
+
+RUN 4 ms
+PRESS CS_GH
+RUN 1 cycle
+EXPECT keyboard-report Key_X Key_LeftShift # report: { e1 }
+EXPECT keyboard-report Key_X Key_LeftShift Key_G # report: { e1 10 }
+
+RUN 4 ms
+RELEASE x
+RUN 1 cycle
+EXPECT keyboard-report Key_LeftShift Key_G # report: { e1 10 }
+
+RUN 4 ms
+RELEASE CS_GH
+RUN 1 cycle
+EXPECT keyboard-report Key_LeftShift # report: { e1 }
+EXPECT keyboard-report empty
+
+RUN 5 ms
+
+# ==============================================================================
+NAME Rollover from shifted to CharShift lower
+
+RUN 4 ms
+PRESS Y
+RUN 1 cycle
+EXPECT keyboard-report Key_LeftShift # report: { e1 }
+EXPECT keyboard-report Key_LeftShift Key_Y
+
+RUN 4 ms
+PRESS CS_ab
+RUN 1 cycle
+EXPECT keyboard-report Key_Y
+EXPECT keyboard-report Key_Y Key_A
+
+RUN 4 ms
+RELEASE Y
+RUN 1 cycle
+EXPECT keyboard-report Key_A
+
+RUN 4 ms
+RELEASE CS_ab
+RUN 1 cycle
+EXPECT keyboard-report empty
+
+RUN 5 ms