Assert tests on the first failure. (#4952)

* Assert tests on the first failure. Disable pop-up message box on assertion.

* Fix format and code style

* Move MSVC dependent code to ifdef

tests/test.cpp

-/*
+/*
  * Copyright 2014 Google Inc. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -2083,6 +2083,7 @@ int FlatBufferTests() {
 }
 
 int main(int /*argc*/, const char * /*argv*/ []) {
+  InitTestEngine();
 
   FlatBufferTests();
   FlatBufferBuilderTest();

tests/test_assert.cpp

+#ifdef _MSC_VER
+#  include <assert.h>
+#  include <crtdbg.h>
+#endif
+
 #include "test_assert.h"
 
 int testing_fails = 0;
@@ -6,8 +11,10 @@ void TestFail(const char *expval, const char *val, const char *exp,
               const char *file, int line, const char *func) {
   TEST_OUTPUT_LINE("VALUE: \"%s\"", expval);
   TEST_OUTPUT_LINE("EXPECTED: \"%s\"", val);
-  TEST_OUTPUT_LINE("TEST FAILED: %s:%d, %s in %s", file, line, exp, func? func : "");
+  TEST_OUTPUT_LINE("TEST FAILED: %s:%d, %s in %s", file, line, exp,
+                   func ? func : "");
   testing_fails++;
+  assert(0);  // assert on first failure under debug
 }
 
 void TestEqStr(const char *expval, const char *val, const char *exp,
@@ -15,3 +22,31 @@ void TestEqStr(const char *expval, const char *val, const char *exp,
   if (strcmp(expval, val) != 0) { TestFail(expval, val, exp, file, line); }
 }
 
+#ifdef _MSC_VER
+// Without this hook function the message box not suppressed.
+int msvc_no_dialog_box_on_assert(int rpt_type, char *msg, int *ret_val) {
+  (void)ret_val;
+  TEST_OUTPUT_LINE("TEST ASSERTED: %d: %s", rpt_type, msg);
+  return 1;
+}
+#endif
+
+void InitTestEngine() {
+  testing_fails = 0;
+  // Disable stdout buffering to prevent information lost on assertion or core
+  // dump.
+  setvbuf(stdout, NULL, _IONBF, 0);
+  setvbuf(stderr, NULL, _IONBF, 0);
+
+  // clang-format off
+
+  #ifdef _MSC_VER
+    // Suppress pop-up message box on assertion (MSVC2010, MSVC2012).
+    // This message box hangs CI-test on the hour until timeout expired.
+    // Default mode is file, file is stderr.
+    _CrtSetReportMode(_CRT_ASSERT, _CRTDBG_MODE_FILE | _CRTDBG_MODE_DEBUG);
+    _CrtSetReportFile(_CRT_ASSERT, _CRTDBG_FILE_STDERR);
+    _CrtSetReportHook(msvc_no_dialog_box_on_assert);
+  #endif
+  // clang-format on
+}

tests/test_assert.h

@@ -17,6 +17,9 @@
 
 extern int testing_fails;
 
+// Prepare test engine (MSVC assertion setup, etc)
+void InitTestEngine();
+
 void TestFail(const char *expval, const char *val, const char *exp,
               const char *file, int line, const char *func = 0);