Commit 397a944b authored by Alexey Spiridonov's avatar Alexey Spiridonov Committed by afrind

Add CaptureFD for log testing (and some glog patterns)

Summary:
Without a gadget like this, it's really hard to test logging output. With it, it's really easy. I found about 50 callsites to the various functions across several projects, so folly seems appropriate.

PS The patterns are functions for two reasons:
- Static variables are a pain.
- This leaves the option of adding an optional argument, so you can grep for a particular kind of error string.

Test Plan: unit test

Reviewed By: yfeldblum@fb.com

Subscribers: folly-diffs@, yfeldblum

FB internal diff: D1933439

Signature: t1:1933439:1427345479:5b3d1c6566a026fdbccb16b382211688e327ea1a
parent 133fc50c
...@@ -19,10 +19,13 @@ ...@@ -19,10 +19,13 @@
#include <sys/types.h> #include <sys/types.h>
#include <sys/stat.h> #include <sys/stat.h>
#include <fcntl.h> #include <fcntl.h>
#include <unistd.h>
#include <boost/regex.hpp> #include <boost/regex.hpp>
#include <folly/Conv.h> #include <folly/Conv.h>
#include <folly/Exception.h> #include <folly/Exception.h>
#include <folly/File.h>
#include <folly/FileUtil.h>
namespace folly { namespace folly {
namespace test { namespace test {
...@@ -134,5 +137,47 @@ bool hasNoPCREPatternMatch(StringPiece pattern, StringPiece target) { ...@@ -134,5 +137,47 @@ bool hasNoPCREPatternMatch(StringPiece pattern, StringPiece target) {
} // namespace detail } // namespace detail
CaptureFD::CaptureFD(int fd) : fd_(fd), readOffset_(0) {
oldFDCopy_ = dup(fd_);
PCHECK(oldFDCopy_ != -1) << "Could not copy FD " << fd_;
int file_fd = open(file_.path().c_str(), O_WRONLY|O_CREAT, 0600);
PCHECK(dup2(file_fd, fd_) != -1) << "Could not replace FD " << fd_
<< " with " << file_fd;
PCHECK(close(file_fd) != -1) << "Could not close " << file_fd;
}
void CaptureFD::release() {
if (oldFDCopy_ != fd_) {
PCHECK(dup2(oldFDCopy_, fd_) != -1) << "Could not restore old FD "
<< oldFDCopy_ << " into " << fd_;
PCHECK(close(oldFDCopy_) != -1) << "Could not close " << oldFDCopy_;
oldFDCopy_ = fd_; // Make this call idempotent
}
}
CaptureFD::~CaptureFD() {
release();
}
std::string CaptureFD::read() {
std::string contents;
std::string filename = file_.path().native();
PCHECK(folly::readFile(filename.c_str(), contents));
return contents;
}
std::string CaptureFD::readIncremental() {
std::string filename = file_.path().native();
// Yes, I know that I could just keep the file open instead. So sue me.
folly::File f(openNoInt(filename.c_str(), O_RDONLY), true);
auto size = lseek(f.fd(), 0, SEEK_END) - readOffset_;
std::unique_ptr<char[]> buf(new char[size]);
auto bytes_read = folly::preadFull(f.fd(), buf.get(), size, readOffset_);
PCHECK(size == bytes_read);
readOffset_ += size;
return std::string(buf.get(), size);
}
} // namespace test } // namespace test
} // namespace folly } // namespace folly
...@@ -139,6 +139,58 @@ namespace detail { ...@@ -139,6 +139,58 @@ namespace detail {
bool hasNoPCREPatternMatch(StringPiece pattern, StringPiece target); bool hasNoPCREPatternMatch(StringPiece pattern, StringPiece target);
} // namespace detail } // namespace detail
/**
* Use these patterns together with CaptureFD and EXPECT_PCRE_MATCH() to
* test for the presence (or absence) of log lines at a particular level:
*
* CaptureFD stderr(2);
* LOG(INFO) << "All is well";
* EXPECT_NO_PCRE_MATCH(glogErrOrWarnPattern(), stderr.readIncremental());
* LOG(ERROR) << "Uh-oh";
* EXPECT_PCRE_MATCH(glogErrorPattern(), stderr.readIncremental());
*/
inline std::string glogErrorPattern() { return ".*(^|\n)E[0-9].*"; }
inline std::string glogWarningPattern() { return ".*(^|\n)W[0-9].*"; }
// Error OR warning
inline std::string glogErrOrWarnPattern() { return ".*(^|\n)[EW][0-9].*"; }
/**
* Temporarily capture a file descriptor by redirecting it into a file.
* You can consume its output either all-at-once or incrementally.
* Great for testing logging (see also glog*Pattern()).
*/
class CaptureFD {
public:
explicit CaptureFD(int fd);
~CaptureFD();
/**
* Restore the captured FD to its original state. It can be useful to do
* this before the destructor so that you can read() the captured data and
* log about it to the formerly captured stderr or stdout.
*/
void release();
/**
* Reads the whole file into a string, but does not remove the redirect.
*/
std::string read();
/**
* Read any bytes that were appended to the file since the last
* readIncremental. Great for testing line-by-line output.
*/
std::string readIncremental();
private:
TemporaryFile file_;
int fd_;
int oldFDCopy_; // equal to fd_ after restore()
off_t readOffset_; // for incremental reading
};
} // namespace test } // namespace test
} // namespace folly } // namespace folly
......
...@@ -115,6 +115,26 @@ TEST(PCREPatternMatch, Simple) { ...@@ -115,6 +115,26 @@ TEST(PCREPatternMatch, Simple) {
EXPECT_NO_PCRE_MATCH(".*ac.*", "gabca"); EXPECT_NO_PCRE_MATCH(".*ac.*", "gabca");
} }
TEST(CaptureFD, GlogPatterns) {
CaptureFD stderr(2);
LOG(INFO) << "All is well";
EXPECT_NO_PCRE_MATCH(glogErrOrWarnPattern(), stderr.readIncremental());
{
LOG(ERROR) << "Uh-oh";
auto s = stderr.readIncremental();
EXPECT_PCRE_MATCH(glogErrorPattern(), s);
EXPECT_NO_PCRE_MATCH(glogWarningPattern(), s);
EXPECT_PCRE_MATCH(glogErrOrWarnPattern(), s);
}
{
LOG(WARNING) << "Oops";
auto s = stderr.readIncremental();
EXPECT_NO_PCRE_MATCH(glogErrorPattern(), s);
EXPECT_PCRE_MATCH(glogWarningPattern(), s);
EXPECT_PCRE_MATCH(glogErrOrWarnPattern(), s);
}
}
int main(int argc, char *argv[]) { int main(int argc, char *argv[]) {
testing::InitGoogleTest(&argc, argv); testing::InitGoogleTest(&argc, argv);
gflags::ParseCommandLineFlags(&argc, &argv, true); gflags::ParseCommandLineFlags(&argc, &argv, true);
......
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