Fix #216 by considering the case of job field with null value

Author: tom-tan

cwltest/plugin.py

@@ -67,7 +67,7 @@ def _run_test_hook_or_plain(
     start_time = time.time()
     reltool = os.path.relpath(test["tool"], start=config.test_basedir)
     tooluri = urljoin(config.test_baseuri, reltool)
-    if "job" in test:
+    if test.get("job", None):
         reljob = os.path.relpath(test["job"], start=config.test_basedir)
         joburi = urljoin(config.test_baseuri, reljob)
     else:

cwltest/utils.py

@@ -440,7 +440,7 @@ def run_test_plain(
 
     reltool = os.path.relpath(test["tool"], start=config.test_basedir)
     tooluri = urljoin(config.test_baseuri, reltool)
-    if "job" in test:
+    if test.get("job", None):
         reljob = os.path.relpath(test["job"], start=config.test_basedir)
         joburi = urljoin(config.test_baseuri, reljob)
     else: