From c8b6844f3f520ecadba15b08ed63161ee9933554 Mon Sep 17 00:00:00 2001
From: YuviPanda <yuvipanda@gmail.com>
Date: Sat, 19 Aug 2023 11:24:35 -0700
Subject: [PATCH] Throw error and exit if config file isn't readable

Fixes https://github.com/pangeo-forge/pangeo-forge-runner/issues/73
---
 pangeo_forge_runner/commands/base.py | 13 +++++++++++--
 tests/unit/test_expand_meta.py       | 10 ++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/pangeo_forge_runner/commands/base.py b/pangeo_forge_runner/commands/base.py
index 30c29593..5201dbca 100644
--- a/pangeo_forge_runner/commands/base.py
+++ b/pangeo_forge_runner/commands/base.py
@@ -211,8 +211,17 @@ def json_excepthook(self, etype, evalue, traceback):
 
     def initialize(self, argv=None):
         super().initialize(argv)
-        # Load traitlets config from a config file if present
-        self.load_config_file(self.config_file)
+        # Load traitlets config from a config file if passed
+        if self.config_file:
+            if os.path.exists(self.config_file):
+                # Throw an explicit error and exit if config file isn't present
+                print(
+                    f"Could not read config from file {self.config_file}. Make sure it exists and is readable",
+                    file=sys.stderr,
+                )
+                sys.exit(1)
+
+            self.load_config_file(self.config_file)
 
         # Allow arbitrary logging config if set
         # We do this first up so any custom logging we set up ourselves
diff --git a/tests/unit/test_expand_meta.py b/tests/unit/test_expand_meta.py
index cb5ee740..e80b3cc5 100644
--- a/tests/unit/test_expand_meta.py
+++ b/tests/unit/test_expand_meta.py
@@ -1,4 +1,6 @@
 import json
+import os
+import secrets
 import subprocess
 
 invocations = [
@@ -75,3 +77,11 @@ def test_expand_meta_no_json():
         out = subprocess.check_output(cmd, encoding="utf-8")
         last_line = out.splitlines()[-1]
         assert json.loads(last_line) == invocation["meta"]
+
+
+def test_missing_config_file():
+    non_existent_path = secrets.token_hex() + ".py"
+    assert not os.path.exists(non_existent_path)
+    cmd = ["pangeo-forge-runner", "expand-meta", "--config", non_existent_path]
+    proc = subprocess.run(cmd, encoding="utf-8")
+    assert proc.returncode == 1