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
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
+#include <unistd.h>
#include <boost/regex.hpp>
#include <folly/Conv.h>
#include <folly/Exception.h>
+#include <folly/File.h>
+#include <folly/FileUtil.h>
namespace folly {
namespace test {
} // 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 folly
bool hasNoPCREPatternMatch(StringPiece pattern, StringPiece target);
} // 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 folly
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[]) {
testing::InitGoogleTest(&argc, argv);
gflags::ParseCommandLineFlags(&argc, &argv, true);