tests/utils.py: Shorten run_playbook for smaller traceback with assert

Most of the content has been moved to the new function _run_playbook to
reduce the traceback output in the case of a test failure.

tests/utils.py

@@ -148,30 +148,6 @@ def write_logs(result, test_name):
         log_file.write(result.stderr.decode("utf-8"))
 
 
-def _run_playbook(playbook):
-    """
-    Create a inventory using a temporary file and run ansible using it.
-
-    The logs of the run will be placed in `tests/logs/`.
-    """
-    with tempfile.NamedTemporaryFile() as inventory_file:
-        inventory_file.write(get_inventory_content())
-        inventory_file.flush()
-        cmd_options = ["-i", inventory_file.name]
-        verbose = os.environ.get("IPA_VERBOSITY", None)
-        if verbose is not None:
-            cmd_options.append(verbose)
-        cmd = ["ansible-playbook"] + cmd_options + [playbook]
-        # pylint: disable=subprocess-run-check
-        process = subprocess.run(
-            cmd, cwd=SCRIPT_DIR, stdout=subprocess.PIPE, stderr=subprocess.PIPE
-        )
-    test_name = get_test_name_from_playbook_path(playbook)
-    write_logs(process, test_name)
-
-    return process
-
-
 def _truncate(lines, charcount, minlines=0):
     output = ""
     line_count = 1
@@ -188,12 +164,11 @@ def _truncate(lines, charcount, minlines=0):
     return output
 
 
-def run_playbook(playbook, allow_failures=False):
+def _run_playbook(playbook):
     """
-    Run an Ansible playbook and assert the return code.
+    Create a inventory using a temporary file and run ansible using it.
 
-    Call ansible (using _run_playbook function) and assert the result of
-    the execution.
+    The logs of the run will be placed in `tests/logs/`.
 
     In case of failure the tail of the error message will be displayed
     as an assertion message.
@@ -201,16 +176,29 @@ def run_playbook(playbook, allow_failures=False):
     The full log of the execution will be available in the directory
     `tests/logs/`.
     """
-    result = _run_playbook(playbook)
-
-    if allow_failures:
-        return result
+    with tempfile.NamedTemporaryFile() as inventory_file:
+        inventory_file.write(get_inventory_content())
+        inventory_file.flush()
+        cmd_options = ["-i", inventory_file.name]
+        verbose = os.environ.get("IPA_VERBOSITY", None)
+        if verbose is not None:
+            cmd_options.append(verbose)
+        cmd = ["ansible-playbook"] + cmd_options + [playbook]
+        process = subprocess.run(
+            cmd, cwd=SCRIPT_DIR, stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE, check=False
+        )
+    test_name = get_test_name_from_playbook_path(playbook)
+    write_logs(process, test_name)
 
+    msg = ""
+    if process.returncode != 0:
         status_code_msg = "ansible-playbook return code: {0}".format(
-        result.returncode
+            process.returncode
         )
-    _stdout = result.stdout.decode("utf8")
-    _stderr = result.stderr.decode("utf8")
+
+        _stdout = process.stdout.decode("utf8")
+        _stderr = process.stderr.decode("utf8")
         # Truncate stdout and stderr in the way that it hopefully
         # shows all important information. At least 15 lines of stdout
         # (Ansible tasks) and remaining from stderr to fill up to
@@ -222,22 +210,31 @@ def run_playbook(playbook, allow_failures=False):
                            minlines=15)
         stderr = _truncate(_stderr.splitlines(), maxlen - len(stdout))
 
-    assert_msg = "\n".join(
+        msg = "\n".join(
             [
                 "",
                 "-" * 30 + " Captured stdout " + "-" * 30,
                 stdout,
                 "-" * 30 + " Captured stderr " + "-" * 30,
-            stderr,
-            "-" * 30 + " Playbook Return Code " + "-" * 30,
-            status_code_msg,
+                stderr
             ]
         )
+        msg += "-" * 30 + " Playbook Return Code " + "-" * 30 + "\n"
+        msg += status_code_msg
+
+    return process, msg
+
 
-    # Need to get the last bytes of msg otherwise Azure
-    #   will cut it out.
-    assert result.returncode == 0, assert_msg[-2500:]
+def run_playbook(playbook, allow_failures=False):
+    """
+    Run an Ansible playbook and assert the return code.
 
+    Call ansible (using _run_playbook function) and assert the result of
+    the execution.
+    """
+    result, assert_msg = _run_playbook(playbook)
+    if not allow_failures:
+        assert result.returncode == 0, assert_msg
     return result