[tests] Add combinedlogslen argument to test_runner.py

Instead of calling combine_logs from test_runner when the environment variable
PYTHON_DEBUG is set, add a combinedlogslen argument. This makes it easier
to call when running locally, and allows a different length of combined logs
to be printed.

.travis.yml

@@ -18,7 +18,6 @@ env:
     - CCACHE_COMPRESS=1
     - BASE_OUTDIR=$TRAVIS_BUILD_DIR/out
     - SDK_URL=https://bitcoincore.org/depends-sources/sdks
-    - PYTHON_DEBUG=1
     - WINEDEBUG=fixme-all
   matrix:
 # ARM
@@ -79,7 +78,7 @@ script:
     - export LD_LIBRARY_PATH=$TRAVIS_BUILD_DIR/depends/$HOST/lib
     - if [ "$RUN_TESTS" = "true" ]; then travis_wait 30 make $MAKEJOBS check VERBOSE=1; fi
     - if [ "$TRAVIS_EVENT_TYPE" = "cron" ]; then extended="--extended --exclude pruning,dbcrash"; fi
-    - if [ "$RUN_TESTS" = "true" ]; then test/functional/test_runner.py --coverage --quiet ${extended}; fi
+    - if [ "$RUN_TESTS" = "true" ]; then test/functional/test_runner.py --combinedlogslen=4000 --coverage --quiet ${extended}; fi
 after_script:
     - echo $TRAVIS_COMMIT_RANGE
     - echo $TRAVIS_COMMIT_LOG

test/functional/test_runner.py

@@ -175,6 +175,7 @@ def main():
                                      epilog='''
     Help text and arguments for individual test script:''',
                                      formatter_class=argparse.RawTextHelpFormatter)
+    parser.add_argument('--combinedlogslen', '-c', type=int, default=0, help='print a combined log (of length n lines) from all test nodes and test framework to the console on failure.')
     parser.add_argument('--coverage', action='store_true', help='generate a basic coverage report for the RPC interface')
     parser.add_argument('--exclude', '-x', help='specify a comma-separated-list of scripts to exclude.')
     parser.add_argument('--extended', action='store_true', help='run the extended test suite in addition to the basic tests')
@@ -267,9 +268,9 @@ def main():
     if not args.keepcache:
         shutil.rmtree("%s/test/cache" % config["environment"]["BUILDDIR"], ignore_errors=True)
 
-    run_tests(test_list, config["environment"]["SRCDIR"], config["environment"]["BUILDDIR"], config["environment"]["EXEEXT"], tmpdir, args.jobs, args.coverage, passon_args)
+    run_tests(test_list, config["environment"]["SRCDIR"], config["environment"]["BUILDDIR"], config["environment"]["EXEEXT"], tmpdir, args.jobs, args.coverage, passon_args, args.combinedlogslen)
 
-def run_tests(test_list, src_dir, build_dir, exeext, tmpdir, jobs=1, enable_coverage=False, args=[]):
+def run_tests(test_list, src_dir, build_dir, exeext, tmpdir, jobs=1, enable_coverage=False, args=[], combined_logs_len=0):
     # Warn if bitcoind is already running (unix only)
     try:
         if subprocess.check_output(["pidof", "bitcoind"]) is not None:
@@ -326,14 +327,14 @@ def run_tests(test_list, src_dir, build_dir, exeext, tmpdir, jobs=1, enable_cove
             print("\n%s%s%s failed, Duration: %s s\n" % (BOLD[1], test_result.name, BOLD[0], test_result.time))
             print(BOLD[1] + 'stdout:\n' + BOLD[0] + stdout + '\n')
             print(BOLD[1] + 'stderr:\n' + BOLD[0] + stderr + '\n')
-            if os.getenv("PYTHON_DEBUG", "") and os.path.isdir(testdir):
-                # Print the logs on travis, so they are preserved when the vm is disposed
-                print('{}Combine the logs and print the last {} lines ...{}'.format(BOLD[1], 4000, BOLD[0]))
+            if combined_logs_len and os.path.isdir(testdir):
+                # Print the final `combinedlogslen` lines of the combined logs
+                print('{}Combine the logs and print the last {} lines ...{}'.format(BOLD[1], combined_logs_len, BOLD[0]))
                 print('\n============')
                 print('{}Combined log for {}:{}'.format(BOLD[1], testdir, BOLD[0]))
                 print('============\n')
                 combined_logs, _ = subprocess.Popen([os.path.join(tests_dir, 'combine_logs.py'), '-c', testdir], universal_newlines=True, stdout=subprocess.PIPE).communicate()
-                print("\n".join(deque(combined_logs.splitlines(), 4000)))
+                print("\n".join(deque(combined_logs.splitlines(), combined_logs_len)))
 
     print_results(test_results, max_len_name, (int(time.time() - time0)))