[espnow] Keep constant send payloads in shared flash tables (#20271)

tests/component_tests/espnow/config/payload_tables.yaml

@@ -0,0 +1,22 @@
+---
+esphome:
+  name: test
+  on_boot:
+    then:
+      - espnow.send:
+          address: 11:22:33:44:55:66
+          data: [0x01, 0x02, 0x03]
+      - espnow.broadcast:
+          data: [0x01, 0x02, 0x03]
+      - espnow.broadcast: "OK"
+      - espnow.broadcast:
+          data: !lambda return {0x09};
+
+esp32:
+  board: esp32dev
+
+wifi:
+  ssid: test
+  password: password1
+
+espnow:

tests/component_tests/espnow/test_payload_tables.py

@@ -0,0 +1,23 @@
+"""Tests for ESP-NOW constant send payloads in shared flash tables."""
+
+from collections.abc import Callable
+from pathlib import Path
+import re
+
+
+def test_constant_payloads_share_tables(
+    generate_main: Callable[[str | Path], str],
+    component_config_path: Callable[[str], Path],
+) -> None:
+    """Equal payloads share one table; lambdas stay templates."""
+    main_cpp = generate_main(component_config_path("payload_tables.yaml"))
+
+    tables = dict(
+        re.findall(
+            r"static constexpr uint8_t (\w+)\[\] PROGMEM = (\{[^}]*\});", main_cpp
+        )
+    )
+    assert sorted(tables.values()) == sorted(["{0x01, 0x02, 0x03}", "{0x4F, 0x4B}"])
+    shared = next(k for k, v in tables.items() if v == "{0x01, 0x02, 0x03}")
+    assert main_cpp.count(f"set_data_static({shared}, 3);") == 2
+    assert "set_data_template(" in main_cpp

tests/components/core/test_templatable_bytes.cpp

@@ -0,0 +1,43 @@
+#include <gtest/gtest.h>
+#include <vector>
+#include "esphome/core/automation.h"
+
+namespace esphome::testing {
+
+static const uint8_t PAYLOAD[] = {1, 2, 3};
+
+static std::vector<uint8_t> repeat(int count) { return std::vector<uint8_t>(count, 7); }
+
+TEST(TemplatableBytesTest, VisitStaticTable) {
+  TemplatableBytes<> bytes;
+  bytes.set_static(PAYLOAD, sizeof(PAYLOAD));
+  std::vector<uint8_t> seen;
+  bytes.visit([&](const uint8_t *data, size_t len) { seen.assign(data, data + len); });
+  EXPECT_EQ(seen, (std::vector<uint8_t>{1, 2, 3}));
+}
+
+TEST(TemplatableBytesTest, VisitWithLargerStackBuffer) {
+  TemplatableBytes<> bytes;
+  bytes.set_static(PAYLOAD, sizeof(PAYLOAD));
+  size_t seen = 0;
+  bytes.visit<256>([&](const uint8_t *, size_t len) { seen = len; });
+  EXPECT_EQ(seen, sizeof(PAYLOAD));
+}
+
+TEST(TemplatableBytesTest, VisitEmptyStaticTable) {
+  TemplatableBytes<> bytes;
+  bytes.set_static(nullptr, 0);
+  size_t seen = 1;
+  bytes.visit([&](const uint8_t *, size_t len) { seen = len; });
+  EXPECT_EQ(seen, 0u);
+}
+
+TEST(TemplatableBytesTest, VisitLambdaWithArgument) {
+  TemplatableBytes<int> bytes;
+  bytes.set_template(repeat);
+  std::vector<uint8_t> seen;
+  bytes.visit([&](const uint8_t *data, size_t len) { seen.assign(data, data + len); }, 4);
+  EXPECT_EQ(seen, (std::vector<uint8_t>(4, 7)));
+}
+
+}  // namespace esphome::testing

tests/unit_tests/test_automation.py

@@ -20,6 +20,7 @@ from esphome.automation import (
     has_non_synchronous_actions,
     literal_with_length,
     maybe_simple_id,
+    progmem_bytes,
     register_apply_action,
     register_apply_condition,
     register_bare_action,
@@ -28,6 +29,7 @@ from esphome.automation import (
     register_parented_condition,
     register_simple_action,
     register_simple_condition,
+    templatable_bytes,
 )
 import esphome.codegen as cg
 import esphome.config_validation as cv
@@ -989,3 +991,48 @@ async def test_apply_condition_string_lambda_paths(
     text = _apply_definition(mock_cg)
     assert expected in text
     assert ("-> std::string {" in text) is called
+
+
+def test_progmem_bytes_shares_equal_payloads() -> None:
+    CORE.config = {}
+    a = progmem_bytes("payload", [1, 2])
+    b = progmem_bytes("payload", b"\x01\x02")
+    assert a is b
+    assert str(progmem_bytes("payload", [])) == "nullptr"
+
+
+@pytest.mark.asyncio
+async def test_templatable_bytes_static_payload() -> None:
+    CORE.config = {}
+    var = MockObj("act", "->")
+    await templatable_bytes(
+        [0xA1, 0x02], [], var.set_code_template, var.set_code_static, "payload"
+    )
+    assert "act->set_code_static(payload, 2);" in CORE.cpp_main_section
+
+
+@pytest.mark.asyncio
+async def test_templatable_bytes_lambda_payload() -> None:
+    CORE.config = {}
+    var = MockObj("act", "->")
+    await templatable_bytes(
+        Lambda("return {0x01, 0x02};"),
+        [],
+        var.set_code_template,
+        var.set_code_static,
+        "payload",
+    )
+    text = CORE.cpp_main_section
+    assert "act->set_code_template(" in text
+    assert "-> std::vector<uint8_t>" in text
+    assert "set_code_static" not in text
+
+
+@pytest.mark.asyncio
+async def test_templatable_bytes_rejects_oversized_payload() -> None:
+    CORE.config = {}
+    var = MockObj("act", "->")
+    with pytest.raises(EsphomeError, match="maximum is 65535"):
+        await templatable_bytes(
+            [0] * 0x10000, [], var.set_code_template, var.set_code_static, "payload"
+        )