pw_unit_test: pw_log unit test event handler

This adds a pw_log based unit test event handler, and switches it to be
the default.

Change-Id: I83808e1e0ffcb0061644a45d4acc1d47f1161f57
diff --git a/pw_unit_test/logging_event_handler.cc b/pw_unit_test/logging_event_handler.cc
new file mode 100644
index 0000000..bf7ba22
--- /dev/null
+++ b/pw_unit_test/logging_event_handler.cc
@@ -0,0 +1,79 @@
+// Copyright 2020 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 "pw_unit_test/logging_event_handler.h"
+
+//#include <cstdarg>
+//#include <cstdio>
+//#include <string_view>
+#include <cstdint>
+
+#include "pw_log/log.h"
+
+namespace pw::unit_test {
+
+void LoggingEventHandler::RunAllTestsStart() {
+  PW_LOG_INFO("[==========] Running all tests.");
+}
+
+void LoggingEventHandler::RunAllTestsEnd(
+    const RunTestsSummary& run_tests_summary) {
+  PW_LOG_INFO("[==========] Done running all tests.");
+  PW_LOG_INFO("[  PASSED  ] %d test(s).", run_tests_summary.passed_tests);
+  if (run_tests_summary.failed_tests) {
+    PW_LOG_ERROR("[  FAILED  ] %d test(s).", run_tests_summary.failed_tests);
+  }
+}
+
+void LoggingEventHandler::TestCaseStart(const TestCase& test_case) {
+  PW_LOG_INFO("[ RUN      ] %s.%s", test_case.suite_name, test_case.test_name);
+}
+
+void LoggingEventHandler::TestCaseEnd(const TestCase& test_case,
+                                      TestResult result) {
+  // Use a switch with no default to detect changes in the test result enum.
+  switch (result) {
+    case TestResult::kSuccess:
+      PW_LOG_INFO(
+          "[       OK ] %s.%s", test_case.suite_name, test_case.test_name);
+      break;
+    case TestResult::kFailure:
+      PW_LOG_ERROR(
+          "[  FAILED  ] %s.%s", test_case.suite_name, test_case.test_name);
+      break;
+  }
+}
+
+void LoggingEventHandler::TestCaseExpect(const TestCase& test_case,
+                                         const TestExpectation& expectation) {
+  if (!verbose_ && expectation.success) {
+    return;
+  }
+
+  const char* result = expectation.success ? "Success" : "Failure";
+  uint32_t level = expectation.success ? PW_LOG_LEVEL_INFO : PW_LOG_LEVEL_ERROR;
+  PW_LOG(level,
+         PW_LOG_NO_FLAGS,
+         "%s:%d: %s",
+         test_case.file_name,
+         expectation.line_number,
+         result);
+  PW_LOG(level, PW_LOG_NO_FLAGS, "      Expected: %s", expectation.expression);
+  PW_LOG(level,
+         PW_LOG_NO_FLAGS,
+         "        Actual: %s",
+         expectation.evaluated_expression);
+}
+
+}  // namespace pw::unit_test