From a87ad66746bb8e4ff754b99bede01806dfb1e79f Mon Sep 17 00:00:00 2001
From: Clyde Stubbs <2366188+clydebarrow@users.noreply.github.com>
Date: Thu, 30 Jul 2026 15:25:17 -0500
Subject: [PATCH] [epaper_spi] Default init sequence to empty not None (#17966)

Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>
---
 .../components/epaper_spi/models/__init__.py  |  2 +-
 .../config/t133a01_no_init_sequence.yaml      | 26 +++++++++++++++++++
 tests/component_tests/epaper_spi/test_init.py | 21 +++++++++++++++
 3 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 tests/component_tests/epaper_spi/config/t133a01_no_init_sequence.yaml

diff --git a/esphome/components/epaper_spi/models/__init__.py b/esphome/components/epaper_spi/models/__init__.py
index 2360b090ffb..34e65061f31 100644
--- a/esphome/components/epaper_spi/models/__init__.py
+++ b/esphome/components/epaper_spi/models/__init__.py
@@ -15,7 +15,7 @@ class EpaperModel:
         self,
         name: str,
         class_name: str,
-        initsequence=None,
+        initsequence=(),
         **defaults,
     ):
         name = name.upper()
diff --git a/tests/component_tests/epaper_spi/config/t133a01_no_init_sequence.yaml b/tests/component_tests/epaper_spi/config/t133a01_no_init_sequence.yaml
new file mode 100644
index 00000000000..1032927146a
--- /dev/null
+++ b/tests/component_tests/epaper_spi/config/t133a01_no_init_sequence.yaml
@@ -0,0 +1,26 @@
+esphome:
+  name: test
+
+esp32:
+  board: esp32-s3-devkitc-1
+  variant: esp32s3
+  framework:
+    type: esp-idf
+
+spi:
+  clk_pin: GPIO18
+  mosi_pin: GPIO19
+
+display:
+  - platform: epaper_spi
+    id: epaper_display
+    model: t133a01
+    dc_pin: GPIO21
+    reset_pin: GPIO38
+    cs_pin: GPIO10
+    cs1_pin: GPIO2
+    busy_pin: GPIO13
+    update_interval: never
+    dimensions:
+      width: 200
+      height: 200
diff --git a/tests/component_tests/epaper_spi/test_init.py b/tests/component_tests/epaper_spi/test_init.py
index 1396c18e3b1..7a0507542e7 100644
--- a/tests/component_tests/epaper_spi/test_init.py
+++ b/tests/component_tests/epaper_spi/test_init.py
@@ -462,3 +462,24 @@ def test_enable_pin_code_generation(
     # Both pin objects must be passed to the display via set_enable_pins() as a
     # std::vector initializer list, in the configured order.
     assert f"set_enable_pins({{{pin_25}, {pin_26}}});" in main_cpp
+
+
+def test_model_with_no_default_init_sequence_generates(
+    generate_main: Callable[[str | Path], str],
+    component_config_path: Callable[[str], Path],
+) -> None:
+    """Test that code generation succeeds for a model with no default init sequence.
+
+    The base "t133a01" model (used directly, not via one of its `.extend()`
+    variants) doesn't override `get_init_sequence()` or pass `initsequence` to
+    its constructor, and the user didn't supply `init_sequence:` either.
+    `EpaperModel.get_init_sequence()` used to default to `None` in this case,
+    which made `flatten_sequence()` raise a `TypeError` during code
+    generation. Regression test for that crash.
+    """
+    main_cpp = generate_main(component_config_path("t133a01_no_init_sequence.yaml"))
+
+    # The generated constructor call takes (name, width, height, init_sequence,
+    # init_sequence_length, ...); a length of 0 confirms the empty init
+    # sequence array was generated instead of raising during code generation.
+    assert re.search(r"epaper_spi::EPaperT133A01\([^;]*,\s*\w+,\s*0\);", main_cpp)