Test the WHO_AM_I table against the datasheet values

esphome/components/lsm6ds/lsm6ds.cpp

@@ -27,7 +27,7 @@ static const LogString *gyro_range_to_str(LSM6DSGyroRange range) {
   }
 }
 
-static const LogString *chip_name_from_who_am_i(uint8_t who_am_i) {
+const LogString *chip_name_from_who_am_i(uint8_t who_am_i) {
   switch (who_am_i) {
     case LSM6DS_WHO_AM_I_LSM6DS3:
       return LOG_STR("LSM6DS3");
@@ -40,6 +40,10 @@ static const LogString *chip_name_from_who_am_i(uint8_t who_am_i) {
   }
 }
 
+uint16_t temperature_sensitivity_from_who_am_i(uint8_t who_am_i) {
+  return who_am_i == LSM6DS_WHO_AM_I_LSM6DS3 ? 16 : 256;
+}
+
 void LSM6DSComponent::setup() {
   MotionComponent::setup();
   uint8_t who_am_i = 0;
@@ -56,8 +60,7 @@ void LSM6DSComponent::setup() {
   }
   ESP_LOGD(TAG, "Found %s (WHO_AM_I = 0x%02X)", LOG_STR_ARG(chip_name), who_am_i);
   this->chip_name_ = chip_name;
-  if (who_am_i == LSM6DS_WHO_AM_I_LSM6DS3)
-    this->temperature_sensitivity_ = 16;
+  this->temperature_sensitivity_ = temperature_sensitivity_from_who_am_i(who_am_i);
 
   // 2. Software reset — clears all registers to defaults
   if (this->write_register(LSM6DS_REG_CTRL3_C, &CTRL3_C_SW_RESET, 1) != i2c::ERROR_OK) {

esphome/components/lsm6ds/lsm6ds.h

@@ -87,6 +87,11 @@ enum LSM6DSGyroODR : uint8_t {
 };
 
 // ── Main component class ─────────────────────────────────────────────────────
+/// Chip name for a WHO_AM_I value, or nullptr when the chip is not supported.
+const LogString *chip_name_from_who_am_i(uint8_t who_am_i);
+/// Temperature sensitivity in LSB/°C for a supported WHO_AM_I value, from the chip's datasheet.
+uint16_t temperature_sensitivity_from_who_am_i(uint8_t who_am_i);
+
 class LSM6DSComponent final : public motion::MotionComponent, public i2c::I2CDevice {
  public:
   void setup() override;

tests/components/lsm6ds/__init__.py

@@ -0,0 +1,6 @@
+from tests.testing_helpers import ComponentManifestOverride
+
+
+def override_manifest(manifest: ComponentManifestOverride) -> None:
+    # lsm6ds declares i2c on its motion platform, which the harness does not walk
+    manifest.dependencies = manifest.dependencies + ["i2c", "motion"]

tests/components/lsm6ds/test_chip_ids.cpp

@@ -0,0 +1,38 @@
+#include <gtest/gtest.h>
+
+#include <cstring>
+
+#include "esphome/components/lsm6ds/lsm6ds.h"
+
+namespace esphome::lsm6ds::testing {
+
+// WHO_AM_I values and temperature sensitivities from ST's datasheets:
+// LSM6DS3 DocID026899, LSM6DS3TR-C DocID030071, LSM6DSO DS12140
+
+static const char *name_of(uint8_t who_am_i) {
+  const LogString *name = chip_name_from_who_am_i(who_am_i);
+  return name == nullptr ? nullptr : LOG_STR_ARG(name);
+}
+
+TEST(LSM6DSChipIds, Lsm6ds3) {
+  EXPECT_STREQ(name_of(0x69), "LSM6DS3");
+  EXPECT_EQ(temperature_sensitivity_from_who_am_i(0x69), 16);
+}
+
+TEST(LSM6DSChipIds, Lsm6ds3trC) {
+  EXPECT_STREQ(name_of(0x6A), "LSM6DS3TR-C");
+  EXPECT_EQ(temperature_sensitivity_from_who_am_i(0x6A), 256);
+}
+
+TEST(LSM6DSChipIds, Lsm6dso) {
+  EXPECT_STREQ(name_of(0x6C), "LSM6DSO");
+  EXPECT_EQ(temperature_sensitivity_from_who_am_i(0x6C), 256);
+}
+
+TEST(LSM6DSChipIds, UnknownIsRejected) {
+  EXPECT_EQ(name_of(0x00), nullptr);
+  EXPECT_EQ(name_of(0x6B), nullptr);
+  EXPECT_EQ(name_of(0xFF), nullptr);
+}
+
+}  // namespace esphome::lsm6ds::testing