From a5231b86df5a9171978f21364c6b92ac6cbf502b Mon Sep 17 00:00:00 2001
From: Mike Crowe <mcrowe@brightsign.biz>
Date: Sat, 22 Jul 2017 14:42:37 +0100
Subject: [PATCH] printf-test: Add check that errno is preserved by
 fmt::sprintf

Since I accidentally added code to PrintfFormatter::format that modified
errno on mingw whilst adding support for '%m', it seems worth having a test
to make sure that can't happen again in the future.
---
 test/printf-test.cc | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/test/printf-test.cc b/test/printf-test.cc
index a0443838..3f25670e 100644
--- a/test/printf-test.cc
+++ b/test/printf-test.cc
@@ -476,6 +476,21 @@ TEST(PrintfTest, Enum) {
   EXPECT_PRINTF("42", "%d", A);
 }
 
+TEST(PrintfTest, ErrnoPreserved) {
+  errno = ENOENT;
+  EXPECT_PRINTF_NO_ARG("testing 1 2 3", "testing 1 2 3");
+  EXPECT_EQ(errno, ENOENT);
+
+  EXPECT_PRINTF("42", "%d", 42);
+  EXPECT_EQ(errno, ENOENT);
+
+  EXPECT_PRINTF(" Hello", "%6s", "Hello");
+  EXPECT_EQ(errno, ENOENT);
+
+  EXPECT_PRINTF_NO_ARG("No such file or directory", "%m");
+  EXPECT_EQ(errno, ENOENT);
+}
+
 TEST(PrintfTest, ErrorMessage) {
   errno = ENOENT;