[libc] android atest compat (#93852)

These changes slighly modify the output of the unittests so that they better
match GTest, so that utilities that parse the expected output from GTest (such
as Android's unit test harness) can read the output from our unit tests.

This allows our unit tests to be run on Android devices.

Add very primitive command line parsing to:
- support --gtest_color=no to disable printing terminal colors.
- recognize --gtest_print_time and print the test time in milliseconds.
  - most of our unit tests run on the order of microseconds, so its useful to
    preserve the existing behavior.  But upsteram GTest ONLY prints time tests
    in milliseconds, and Android's atest expects to be able to parse exactly
    that. Atest always passes --gtest_print_time. The word `took` is removed as
    that also differs from upstream GTest, tripping up parsers.
- ignore other --gtest_* flags

Do so so that atest can parse the output correctly.

Print the test number count before
each run, so that atest can parse this value correctly.

Link: https://android-review.googlesource.com/c/platform/external/llvm-libc/+/3107252
Link: https://google.github.io/googletest/advanced.html#colored-terminal-output
Link: https://google.github.io/googletest/advanced.html#suppressing-the-elapsed-time

libc/test/UnitTest/LibcTest.cpp

@@ -127,19 +127,37 @@ void Test::addTest(Test *T) {
   End = T;
 }
 
-int Test::runTests(const char *TestFilter) {
-  int TestCount = 0;
+int Test::getNumTests() {
+  int N = 0;
+  for (Test *T = Start; T; T = T->Next, ++N)
+    ;
+  return N;
+}
+
+int Test::runTests(const TestOptions &Options) {
+  const char *green = Options.PrintColor ? "\033[32m" : "";
+  const char *red = Options.PrintColor ? "\033[31m" : "";
+  const char *reset = Options.PrintColor ? "\033[0m" : "";
+
+  int TestCount = getNumTests();
+  if (TestCount) {
+    tlog << green << "[==========] " << reset << "Running " << TestCount
+         << " test";
+    if (TestCount > 1)
+      tlog << "s";
+    tlog << " from 1 test suite.\n";
+  }
+
   int FailCount = 0;
   for (Test *T = Start; T != nullptr; T = T->Next) {
     const char *TestName = T->getName();
-    cpp::string StrTestName(TestName);
-    constexpr auto GREEN = "\033[32m";
-    constexpr auto RED = "\033[31m";
-    constexpr auto RESET = "\033[0m";
-    if ((TestFilter != nullptr) && (StrTestName != TestFilter)) {
+
+    if (Options.TestFilter && cpp::string(TestName) != Options.TestFilter) {
+      --TestCount;
       continue;
     }
-    tlog << GREEN << "[ RUN      ] " << RESET << TestName << '\n';
+
+    tlog << green << "[ RUN      ] " << reset << TestName << '\n';
     [[maybe_unused]] const auto start_time = clock();
     RunContext Ctx;
     T->SetUp();
@@ -149,13 +167,13 @@ int Test::runTests(const char *TestFilter) {
     [[maybe_unused]] const auto end_time = clock();
     switch (Ctx.status()) {
     case RunContext::RunResult::Fail:
-      tlog << RED << "[  FAILED  ] " << RESET << TestName << '\n';
+      tlog << red << "[  FAILED  ] " << reset << TestName << '\n';
       ++FailCount;
       break;
     case RunContext::RunResult::Pass:
-      tlog << GREEN << "[       OK ] " << RESET << TestName;
+      tlog << green << "[       OK ] " << reset << TestName;
 #ifdef LIBC_TEST_USE_CLOCK
-      tlog << " (took ";
+      tlog << " (";
       if (start_time > end_time) {
         tlog << "unknown - try rerunning)\n";
       } else {
@@ -164,7 +182,7 @@ int Test::runTests(const char *TestFilter) {
         const uint64_t duration_us = (duration * 1000 * 1000) / CLOCKS_PER_SEC;
         const uint64_t duration_ns =
             (duration * 1000 * 1000 * 1000) / CLOCKS_PER_SEC;
-        if (duration_ms != 0)
+        if (Options.TimeInMs || duration_ms != 0)
           tlog << duration_ms << " ms)\n";
         else if (duration_us != 0)
           tlog << duration_us << " us)\n";
@@ -176,7 +194,6 @@ int Test::runTests(const char *TestFilter) {
 #endif
       break;
     }
-    ++TestCount;
   }
 
   if (TestCount > 0) {
@@ -185,8 +202,8 @@ int Test::runTests(const char *TestFilter) {
          << '\n';
   } else {
     tlog << "No tests run.\n";
-    if (TestFilter) {
-      tlog << "No matching test for " << TestFilter << '\n';
+    if (Options.TestFilter) {
+      tlog << "No matching test for " << Options.TestFilter << '\n';
     }
   }
 

libc/test/UnitTest/LibcTest.h

@@ -100,6 +100,15 @@ bool test(RunContext *Ctx, TestCond Cond, ValType LHS, ValType RHS,
 
 } // namespace internal
 
+struct TestOptions {
+  // If set, then just this one test from the suite will be run.
+  const char *TestFilter = nullptr;
+  // Should the test results print color codes to stdout?
+  bool PrintColor = true;
+  // Should the test results print timing only in milliseconds, as GTest does?
+  bool TimeInMs = false;
+};
+
 // NOTE: One should not create instances and call methods on them directly. One
 // should use the macros TEST or TEST_F to write test cases.
 class Test {
@@ -107,13 +116,14 @@ class Test {
   internal::RunContext *Ctx = nullptr;
 
   void setContext(internal::RunContext *C) { Ctx = C; }
+  static int getNumTests();
 
 public:
   virtual ~Test() {}
   virtual void SetUp() {}
   virtual void TearDown() {}
 
-  static int runTests(const char *);
+  static int runTests(const TestOptions &Options);
 
 protected:
   static void addTest(Test *T);

libc/test/UnitTest/LibcTestMain.cpp

@@ -7,16 +7,46 @@
 //===----------------------------------------------------------------------===//
 
 #include "LibcTest.h"
+#include "src/__support/CPP/string_view.h"
 
-static const char *getTestFilter(int argc, char *argv[]) {
-  return argc > 1 ? argv[1] : nullptr;
+using LIBC_NAMESPACE::cpp::string_view;
+using LIBC_NAMESPACE::testing::TestOptions;
+
+namespace {
+
+// A poor-man's getopt_long.
+// Run unit tests with --gtest_color=no to disable printing colors, or
+// --gtest_print_time to print timings in milliseconds only (as GTest does, so
+// external tools such as Android's atest may expect that format to parse the
+// output). Other command line flags starting with --gtest_ are ignored.
+// Otherwise, the last command line arg is used as a test filter, if command
+// line args are specified.
+TestOptions parseOptions(int argc, char **argv) {
+  TestOptions Options;
+
+  for (int i = 1; i < argc; ++i) {
+    string_view arg{argv[i]};
+
+    if (arg == "--gtest_color=no")
+      Options.PrintColor = false;
+    else if (arg == "--gtest_print_time")
+      Options.TimeInMs = true;
+    // Ignore other unsupported gtest specific flags.
+    else if (arg.starts_with("--gtest_"))
+      continue;
+    else
+      Options.TestFilter = argv[i];
+  }
+
+  return Options;
 }
 
+} // anonymous namespace
+
 extern "C" int main(int argc, char **argv, char **envp) {
   LIBC_NAMESPACE::testing::argc = argc;
   LIBC_NAMESPACE::testing::argv = argv;
   LIBC_NAMESPACE::testing::envp = envp;
 
-  const char *TestFilter = getTestFilter(argc, argv);
-  return LIBC_NAMESPACE::testing::Test::runTests(TestFilter);
+  return LIBC_NAMESPACE::testing::Test::runTests(parseOptions(argc, argv));
 }

libc/test/utils/UnitTest/testfilter_test.cpp

@@ -8,6 +8,8 @@
 
 #include "test/UnitTest/LibcTest.h"
 
+using LIBC_NAMESPACE::testing::TestOptions;
+
 TEST(LlvmLibcTestFilterTest, CorrectFilter) {}
 
 TEST(LlvmLibcTestFilterTest, CorrectFilter2) {}
@@ -17,22 +19,22 @@ TEST(LlvmLibcTestFilterTest, IncorrectFilter) {}
 TEST(LlvmLibcTestFilterTest, NoFilter) {}
 
 TEST(LlvmLibcTestFilterTest, CheckCorrectFilter) {
-  ASSERT_EQ(LIBC_NAMESPACE::testing::Test::runTests(
-                "LlvmLibcTestFilterTest.NoFilter"),
-            0);
-  ASSERT_EQ(LIBC_NAMESPACE::testing::Test::runTests(
-                "LlvmLibcTestFilterTest.IncorrFilter"),
-            1);
-  ASSERT_EQ(LIBC_NAMESPACE::testing::Test::runTests(
-                "LlvmLibcTestFilterTest.CorrectFilter"),
-            0);
-  ASSERT_EQ(LIBC_NAMESPACE::testing::Test::runTests(
-                "LlvmLibcTestFilterTest.CorrectFilter2"),
-            0);
+  TestOptions Options;
+  Options.TestFilter = "LlvmLibcTestFilterTest.NoFilter";
+  ASSERT_EQ(LIBC_NAMESPACE::testing::Test::runTests(Options), 0);
+
+  Options.TestFilter = "LlvmLibcTestFilterTest.IncorrFilter";
+  ASSERT_EQ(LIBC_NAMESPACE::testing::Test::runTests(Options), 1);
+
+  Options.TestFilter = "LlvmLibcTestFilterTest.CorrectFilter";
+  ASSERT_EQ(LIBC_NAMESPACE::testing::Test::runTests(Options), 0);
+
+  Options.TestFilter = "LlvmLibcTestFilterTest.CorrectFilter2";
+  ASSERT_EQ(LIBC_NAMESPACE::testing::Test::runTests(Options), 0);
 }
 
 int main() {
-  LIBC_NAMESPACE::testing::Test::runTests(
-      "LlvmLibcTestFilterTest.CheckCorrectFilter");
+  TestOptions Options{"LlvmLibcTestFilterTest.NoFilter", /*PrintColor=*/true};
+  LIBC_NAMESPACE::testing::Test::runTests(Options);
   return 0;
 }