Improvements for MachMultiprocess

util/test/mac/mach_multiprocess_test.cc

Index: util/test/mac/mach_multiprocess_test.cc
diff --git a/util/test/mac/mach_multiprocess_test.cc b/util/test/mac/mach_multiprocess_test.cc
index b0429cdbbc9eacb569a3dea2f942ed0b7da03aef..a8639978f764e7a6a93470862ffe0cdabdef0469 100644
--- a/util/test/mac/mach_multiprocess_test.cc
+++ b/util/test/mac/mach_multiprocess_test.cc
@@ -14,6 +14,8 @@
 
 #include "util/test/mac/mach_multiprocess.h"
 
+#include <unistd.h>
+
 #include "base/basictypes.h"
 #include "gtest/gtest.h"
 #include "util/file/fd_io.h"
@@ -32,27 +34,46 @@ class TestMachMultiprocess final : public MachMultiprocess {
 
  protected:
   // The base class will have already exercised the Mach ports for IPC and the
-  // child task port. Just make sure that the pipe is set up correctly.
+  // child task port. Just make sure that the pipe is set up correctly and that
+  // ChildPID() works as expected.
   virtual void Parent() override {
-    int fd = PipeFD();
-
+    int read_fd = ReadPipeFD();
     char c;
-    ssize_t rv = ReadFD(fd, &c, 1);
+    ssize_t rv = ReadFD(read_fd, &c, 1);
     ASSERT_EQ(1, rv) << ErrnoMessage("read");
     EXPECT_EQ('M', c);
 
+    pid_t pid;
+    rv = ReadFD(read_fd, &pid, sizeof(pid));
+    ASSERT_EQ(static_cast<ssize_t>(sizeof(pid)), rv) << ErrnoMessage("read");
+    EXPECT_EQ(pid, ChildPID());
+
+    int write_fd = WritePipeFD();
+    c = 'm';
+    rv = WriteFD(write_fd, &c, 1);
+    ASSERT_EQ(1, rv) << ErrnoMessage("write");
+
     // The child will close its end of the pipe and exit. Make sure that the
     // parent sees EOF.
-    rv = ReadFD(fd, &c, 1);
+    rv = ReadFD(read_fd, &c, 1);
     ASSERT_EQ(0, rv) << ErrnoMessage("read");
   }
 
   virtual void Child() override {
-    int fd = PipeFD();
+    int write_fd = WritePipeFD();
 
     char c = 'M';
-    ssize_t rv = WriteFD(fd, &c, 1);
+    ssize_t rv = WriteFD(write_fd, &c, 1);
     ASSERT_EQ(1, rv) << ErrnoMessage("write");
+
+    pid_t pid = getpid();
+    rv = WriteFD(write_fd, &pid, sizeof(pid));
+    ASSERT_EQ(static_cast<ssize_t>(sizeof(pid)), rv) << ErrnoMessage("write");
+
+    int read_fd = ReadPipeFD();
+    rv = ReadFD(read_fd, &c, 1);
+    ASSERT_EQ(1, rv) << ErrnoMessage("read");
+    EXPECT_EQ('m', c);
   }
 
  private: