Reboot test: Initialize fake clock

[ Merge of http://go/wvgerrit/143630 ]

When we run a test with the fake clock, the clock had been initialized
to the current time, or to 0. This causes a problem for reboot tests
because the clock might go backwards over the reboot. With this
change, we monitor the clock at the end of one reboot pass and
initialize the clock for the next pass based on the previous value.

Bug: 26163469
Test: GtsMediaTestCases on sunfish
Change-Id: Ibd0024f963634382af70553fced38da6e1d857d2

libwvdrmengine/cdm/core/test/reboot_test.cpp

@@ -11,6 +11,7 @@
 #include <sstream>
 
 #include "log.h"
+#include "test_sleep.h"
 
 using wvutil::a2b_hex;
 using wvutil::FileSystem;
@@ -227,6 +228,23 @@ void RebootTest::TearDown() {
   WvCdmTestBase::TearDown();
 }
 
+int64_t RebootTest::LoadTime(const std::string& key) {
+  int64_t value = 0;
+  std::istringstream input(persistent_data_[key]);
+  input >> value;
+  if (input.fail()) {
+    LOGE("Could not parse time '%s'", persistent_data_[key].c_str());
+  }
+  if (!input.eof()) {
+    LOGE("Extra text at end of time '%s'", persistent_data_[key].c_str());
+  }
+  return value;
+}
+
+void RebootTest::SaveTime(const std::string& key, int64_t time) {
+  persistent_data_[key] = std::to_string(time);
+}
+
 /** Test the dump and restore functions above. This does not test CDM
     functionality. */
 TEST_F(RebootTest, TestDumpUtil) {
@@ -277,4 +295,20 @@ TEST_F(RebootTest, FilesArePersistent) {
   }
 }
 
+/** Verify that the clock moves forward over a reboot. */
+TEST_F(RebootTest, TimeMovesForward) {
+  wvutil::TestSleep::Sleep(2);
+  const int64_t start = wvutil::Clock().GetCurrentTime();
+  wvutil::TestSleep::Sleep(2);
+  const int64_t end = wvutil::Clock().GetCurrentTime();
+  EXPECT_NEAR(end - start, 2.0, 1.0);
+  const std::string key = "end_time";
+  if (test_pass() == 0) {
+    // Save off the end of pass 1.
+    SaveTime(key, end);
+  } else {
+    int64_t previous_end = LoadTime(key);
+    EXPECT_LT(previous_end, start);
+  }
+}
 }  // namespace wvcdm