check_call_suppress_output: Print errors.

Author: samsrabin

test/test_utils/git_helpers.py

@@ -6,23 +6,23 @@
 
 def make_git_repo():
     """Turn the current directory into an empty git repository"""
-    check_call_suppress_output(['git', 'init'])
+    check_call_suppress_output(" ".join(['git', 'init']))
 
 def add_git_commit():
     """Add a git commit in the current directory"""
     with open('README', 'a') as myfile:
         myfile.write('more info')
-    check_call_suppress_output(['git', 'add', 'README'])
-    check_call_suppress_output(['git', 'commit', '-m', 'my commit message'])
+    check_call_suppress_output(" ".join(['git', 'add', 'README']))
+    check_call_suppress_output("git commit -m 'my commit message'")
 
 def checkout_git_branch(branchname):
     """Checkout a new branch in the current directory"""
-    check_call_suppress_output(['git', 'checkout', '-b', branchname])
+    check_call_suppress_output(" ".join(['git', 'checkout', '-b', branchname]))
 
 def make_git_tag(tagname):
     """Make a lightweight tag at the current commit"""
-    check_call_suppress_output(['git', 'tag', '-m', 'making a tag', tagname])
+    check_call_suppress_output("git tag -m 'making a tag' " + tagname)
 
 def checkout_git_ref(refname):
     """Checkout the given refname in the current directory"""
-    check_call_suppress_output(['git', 'checkout', refname])
+    check_call_suppress_output(" ".join(['git', 'checkout', refname]))

test/test_utils/test_helpers.py

@@ -1,9 +1,22 @@
 """General-purpose functions to help with testing"""
 
-import os
 import subprocess
 
 def check_call_suppress_output(args):
-    """Make a check_call call with the given args, suppressing all output"""
-    with open(os.devnull, 'w') as devnull:
-        subprocess.check_call(args, stdout=devnull)
+    """Make a subprocess call with the given args, suppressing all output unless there's an error"""
+    try:
+        subprocess.run(
+            args,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            text=True,
+            check=True,
+            shell=True,
+        )
+    except subprocess.CalledProcessError as e:
+        print(f"Command failed with exit code {e.returncode}: {e.cmd}")
+        print("stdout:")
+        print(e.stdout)
+        print("stderr:")
+        print(e.stderr)
+        raise