Improve backtrace test

Check that setting terminate handler doesn't change the way a process
terminates on unhandled exception.

2 files changed, 83 insertions, 17 deletions

diff --git a/tests/backtrace/driver.cxx b/tests/backtrace/driver.cxx
index 5fd9223..33967cd 100644
--- a/tests/backtrace/driver.cxx
+++ b/tests/backtrace/driver.cxx
@@ -24,9 +24,11 @@ import std.io;
 import std.core;
 #endif
 import butl.process;
+import butl.fdstream;
 import butl.backtrace;
 #else
 #include <libbutl/process.mxx>
+#include <libbutl/fdstream.mxx>
 #include <libbutl/backtrace.mxx>
 #endif
 
@@ -46,31 +48,55 @@ namespace test
 
 static terminate_handler def_term_handler;
 
-// Usage: argv[0] [-c]
+// Usages:
 //
-// Print the backtrace for an unhandled exception.
+// argv[0] [-q]
+// argv[0] -c [-b]
+//
+// In the first form run the child processes throwing unhandled exception,
+// first of which sets up the backtrace-printing handler prior to throwing,
+// and make sure that they terminate in the same way (abnormally or with the
+// same exit status). Exit with the zero code if that's the case and the
+// children terminated abnormally or with non-zero code and exit with the one
+// code otherwise. Redirect stderr to /dev/null for the first child if
+// requested (-q) and always for the second one.
+//
+// In the second form run as a child process that optionally sets up the
+// backtrace-printing terminate handler (-b) and throws unhandled exception.
 //
-// -c
-//    Run as a child process that sets up the backtrace-printing terminate
-//    handler and throws unhandled exception.
 int
 main (int argc, const char* argv[])
 {
-  // Not to cause the testscript to fail due to the abnormal test driver
-  // termination, delegate the unhandled exception backtrace printing to the
-  // child process.
-  //
   bool child (false);
+  bool backtrace (false);
+  bool quiet (false);
+
   for (int i (1); i != argc; ++i)
   {
     string o (argv[i]);
 
     if (o == "-c")
+    {
       child = true;
+    }
+    else if (o == "-b")
+    {
+      assert (child);
+      backtrace = true;
+    }
+    else if (o == "-q")
+    {
+      assert (!child);
+      quiet = true;
+    }
     else
+    {
       assert (false);
+    }
   }
 
+  // Run as a child.
+  //
   if (child)
   {
     // Disable dumping core file on POSIX.
@@ -80,18 +106,50 @@ main (int argc, const char* argv[])
     assert (setrlimit (RLIMIT_CORE, &rlim) == 0);
 #endif
 
-    def_term_handler = set_terminate ([]()
-                                      {
-                                        cerr << backtrace ();
+    if (backtrace)
+    {
+      def_term_handler = set_terminate ([]()
+                                        {
+                                          cerr << butl::backtrace ();
 
-                                        if (def_term_handler != nullptr)
-                                          def_term_handler ();
-                                      });
+                                          if (def_term_handler != nullptr)
+                                            def_term_handler ();
+                                        });
+    }
 
     return test::func ();
   }
 
-  // Report failure with non-zero code if child succeeds.
+  // Run as a parent.
   //
-  return process_run (0, 1, 2, argv[0], "-c") ? 1 : 0;
+  auto_fd null (fdnull ());
+  process_exit pe1 (process_run (0                       /* stdin */,
+                                 1                       /* stdout */,
+                                 quiet ? null.get () : 2 /* stderr */,
+                                 argv[0], "-c", "-b"));
+
+  if (pe1)
+  {
+    cerr << "error: child exited with zero code" << endl;
+    return 1;
+  }
+
+  // Always run quiet.
+  //
+  process_exit pe2 (process_run (0    /* stdin */,
+                                 1    /* stdout */,
+                                 null /* stderr */,
+                                 argv[0], "-c"));
+
+  if (!(pe1.normal () == pe2.normal () &&
+        (!pe1.normal () || pe1.code () == pe2.code ())))
+  {
+    cerr << "error: child processes terminated differently:" << endl <<
+            "  info: with backtrace: "    << pe1 << endl <<
+            "  info: without backtrace: " << pe2 << endl;
+
+    return 1;
+  }
+
+  return 0;
 }
diff --git a/tests/backtrace/testscript b/tests/backtrace/testscript
index bdcd147..df1b7a1 100644
--- a/tests/backtrace/testscript
+++ b/tests/backtrace/testscript
@@ -18,3 +18,11 @@ if ($tclass == 'linux' || $tclass == 'macos' || $tsys == 'freebsd')
     %.*
     EOE
 }
+else
+{
+  # On OSes where backtrace() is not supported we just check that setting the
+  # terminate handler doesn't change the way a process terminates on the
+  # unhandled exception (see driver.cxx for details).
+  #
+  $* -q
+}