platform/chrome: cros_ec_proto: add Kunit test for getting legacy info

cros_ec_get_proto_info_legacy() expects to receive
sizeof(struct ec_response_hello) from send_command().  The payload is
valid only if the return value is positive.

Add a Kunit test for returning 0 from send_command() in
cros_ec_get_proto_info_legacy().
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
Link: https://lore.kernel.org/r/20220609084957.3684698-12-tzungbi@kernel.org

drivers/platform/chrome/cros_ec_proto_test.c

@@ -751,6 +751,54 @@ static void cros_ec_proto_test_query_all_legacy_data_error(struct kunit *test)
 	}
 }
 
+static void cros_ec_proto_test_query_all_legacy_return0(struct kunit *test)
+{
+	struct cros_ec_proto_test_priv *priv = test->priv;
+	struct cros_ec_device *ec_dev = &priv->ec_dev;
+	struct ec_xfer_mock *mock;
+	int ret;
+
+	/* For cros_ec_get_proto_info() without passthru. */
+	{
+		mock = cros_kunit_ec_xfer_mock_addx(test, 0, EC_RES_INVALID_COMMAND, 0);
+		KUNIT_ASSERT_PTR_NE(test, mock, NULL);
+	}
+
+	/* For cros_ec_get_proto_info_legacy(). */
+	{
+		mock = cros_kunit_ec_xfer_mock_add(test, 0);
+		KUNIT_ASSERT_PTR_NE(test, mock, NULL);
+	}
+
+	cros_ec_proto_test_query_all_pretest(test);
+	ret = cros_ec_query_all(ec_dev);
+	KUNIT_EXPECT_EQ(test, ret, -EPROTO);
+	KUNIT_EXPECT_EQ(test, ec_dev->proto_version, EC_PROTO_VERSION_UNKNOWN);
+
+	/* For cros_ec_get_proto_info() without passthru. */
+	{
+		mock = cros_kunit_ec_xfer_mock_next();
+		KUNIT_EXPECT_PTR_NE(test, mock, NULL);
+
+		KUNIT_EXPECT_EQ(test, mock->msg.version, 0);
+		KUNIT_EXPECT_EQ(test, mock->msg.command, EC_CMD_GET_PROTOCOL_INFO);
+		KUNIT_EXPECT_EQ(test, mock->msg.insize,
+				sizeof(struct ec_response_get_protocol_info));
+		KUNIT_EXPECT_EQ(test, mock->msg.outsize, 0);
+	}
+
+	/* For cros_ec_get_proto_info_legacy(). */
+	{
+		mock = cros_kunit_ec_xfer_mock_next();
+		KUNIT_EXPECT_PTR_NE(test, mock, NULL);
+
+		KUNIT_EXPECT_EQ(test, mock->msg.version, 0);
+		KUNIT_EXPECT_EQ(test, mock->msg.command, EC_CMD_HELLO);
+		KUNIT_EXPECT_EQ(test, mock->msg.insize, sizeof(struct ec_response_hello));
+		KUNIT_EXPECT_EQ(test, mock->msg.outsize, sizeof(struct ec_params_hello));
+	}
+}
+
 static void cros_ec_proto_test_query_all_no_mkbp(struct kunit *test)
 {
 	struct cros_ec_proto_test_priv *priv = test->priv;
@@ -1135,6 +1183,7 @@ static struct kunit_case cros_ec_proto_test_cases[] = {
 	KUNIT_CASE(cros_ec_proto_test_query_all_legacy_xfer_error),
 	KUNIT_CASE(cros_ec_proto_test_query_all_legacy_return_error),
 	KUNIT_CASE(cros_ec_proto_test_query_all_legacy_data_error),
+	KUNIT_CASE(cros_ec_proto_test_query_all_legacy_return0),
 	KUNIT_CASE(cros_ec_proto_test_query_all_no_mkbp),
 	KUNIT_CASE(cros_ec_proto_test_query_all_no_host_sleep),
 	KUNIT_CASE(cros_ec_proto_test_query_all_default_wake_mask_return_error),