Don't attempt to separately close the underlying file descriptor in the format other test

Summary: Windows automatically closes the underlying file descriptor when you call fclose, however fclose is not a function that can be easily overriden in the portability layer, so choose to just not call `close` on Windows instead.

Reviewed By: yfeldblum

Differential Revision: D4190524

fbshipit-source-id: a68edccd04e63f89c178ade584fa7192845773f8

folly/Portability.h

@@ -321,4 +321,10 @@ constexpr auto kIsLinux = true;
 #else
 constexpr auto kIsLinux = false;
 #endif
+
+#if defined(_WIN32)
+constexpr auto kIsWindows = true;
+#else
+constexpr auto kIsWindows = false;
+#endif
 }

folly/test/FormatOtherTest.cpp

@@ -20,10 +20,11 @@
 
 #include <folly/FBVector.h>
 #include <folly/FileUtil.h>
+#include <folly/Portability.h>
 #include <folly/dynamic.h>
 #include <folly/json.h>
-#include <folly/small_vector.h>
 #include <folly/portability/GTest.h>
+#include <folly/small_vector.h>
 
 using namespace folly;
 
@@ -33,7 +34,13 @@ TEST(FormatOther, file) {
   {
     int fds[2];
     CHECK_ERR(pipe(fds));
-    SCOPE_EXIT { closeNoInt(fds[1]); };
+    SCOPE_EXIT {
+      // fclose on Windows automatically closes the underlying
+      // file descriptor.
+      if (!kIsWindows) {
+        closeNoInt(fds[1]);
+      }
+    };
     {
       FILE* fp = fdopen(fds[1], "wb");
       PCHECK(fp);