pw_trace: Add pw_trace:null as default backend
This module is added to act as the default backend for pw_trace where
trace is disabled. With this module, applications would not be required
to set a backend. This backend is implemented with empty functions and
handles unused variables as well.
Test: presubmit involves tests. But an application without backend is
set.
Bug: b/202193001
Change-Id: I676d49ffedf64e5ce493f188349b5a4d8ba17153
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/68141
Reviewed-by: Wyatt Hepler <hepler@google.com>
Reviewed-by: Rob Oliver <rgoliver@google.com>
Commit-Queue: Yuanyao Zhong <yyzhong@google.com>
diff --git a/pw_trace/trace_null_test.cc b/pw_trace/trace_null_test.cc
new file mode 100644
index 0000000..d82714d
--- /dev/null
+++ b/pw_trace/trace_null_test.cc
@@ -0,0 +1,30 @@
+// Copyright 2021 The Pigweed Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not
+// use this file except in compliance with the License. You may obtain a copy of
+// the License at
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations under
+// the License.
+
+#include "gtest/gtest.h"
+#include "pw_trace/internal/null.h"
+
+#define PW_TRACE_MODULE_NAME "this test!"
+
+extern "C" bool CTest();
+
+namespace {
+
+TEST(TraceNull, PW_TRACE) { PW_TRACE(0, 1, "label", "group", 2); }
+
+TEST(TraceNull, PW_TRACE_DATA) {
+ PW_TRACE_DATA(0, 1, "label", "group", 2, "type", "data", 1);
+}
+
+} // namespace