specific exception for failing subprocess

integration/test_grid_manager.py

@@ -190,8 +190,5 @@ def test_reject_storage_server(reactor, request, storage_nodes, temp_dir, introd
             stdin="some content" * 200,
         )
         assert False, "Should get a failure"
-    except Exception as e:
-        # depending on the full output being in the error-message
-        # here; see util.py
-        assert 'UploadUnhappinessError' in str(e)
-        print("found expected UploadUnhappinessError")
+    except util.ProcessFailed as e:
+        assert 'UploadUnhappinessError' in e.output.getvalue()

integration/test_servers_of_happiness.py

@@ -42,8 +42,8 @@ def test_upload_immutable(reactor, temp_dir, introducer_furl, flog_gatherer, sto
     try:
         yield proto.done
         assert False, "should raise exception"
-    except Exception as e:
-        assert "UploadUnhappinessError" in str(e)
+    except util.ProcessFailed as e:
+        assert "UploadUnhappinessError" in e.output.getvalue()
 
     output = proto.output.getvalue()
     assert "shares could be placed on only" in output

integration/util.py

@@ -32,6 +32,20 @@ class _ProcessExitedProtocol(ProcessProtocol):
         self.done.callback(None)
 
 
+class ProcessFailed(Exception):
+    """
+    A subprocess has failed.
+
+    :ivar ProcessTerminated reason: the original reason from .processExited
+
+    :ivar StringIO output: all stdout and stderr collected to this point.
+    """
+
+    def __init__(self, reason, output):
+        self.reason = reason
+        self.output = output
+
+
 class _CollectOutputProtocol(ProcessProtocol):
     """
     Internal helper. Collects all output (stdout + stderr) into
@@ -54,13 +68,7 @@ class _CollectOutputProtocol(ProcessProtocol):
 
     def processExited(self, reason):
         if not isinstance(reason.value, ProcessDone):
-            #self.done.errback(reason)
-            self.done.errback(RuntimeError(
-                "Process failed: {}\nOutput:\n{}".format(
-                    reason,
-                    self.output.getvalue(),
-                )
-            ))
+            self.done.errback(ProcessFailed(reason, self.output))
 
     def outReceived(self, data):
         self.output.write(data)