add stderr attr for easy access

manifold/utilities/error.py

@@ -146,6 +146,8 @@ class Classifier:
 		self._stdout = StringIO()
 		self._stderr = StringIO()
 		self._pipe_manager = wurlitzer.Wurlitzer(stdout=self._stdout, stderr=self._stderr)
+		self.stdout = None
+		self.stderr = None
 
 	def __enter__(self):
 		self._pipe_manager.__enter__()
@@ -155,14 +157,16 @@ class Classifier:
 		# Closeout pipe manager
 		self._pipe_manager.__exit__(exc_type, exc_val, exc_tb)
 
-		# close pipes
+		# close pipes and read
 		self._stdout.seek(0)
 		self._stderr.seek(0)
 
-		stderr = self._stderr.read()
-		if stderr:
+		self.stdout = self._stdout.read()
+		self.stderr = self._stderr.read()
+
+		if self.stderr:
 			# TODO make this more sophisticated / controllable
-			logging.error(stderr)
+			logging.error(self.stderr)
 
 		# Classify error
 		c = self.classify(exc_val)

tests/utilities/test_error.py

@@ -121,5 +121,31 @@ class TestLalRules:
 			with error.classify(rules=[error.LAL_RULE_SIM_INPUT_DOMAIN]) as c:
 				_ = lalsim.SimInspiralFD(**parameters)
 
-		print(c)
-
+	def test_stderr_capture(self):
+		parameters = {
+			'm1': -1,  # Invalid input of negative mass
+			'm2': 1,
+			'S1x': 0.,
+			'S1y': 0.,
+			'S1z': 0.,
+			'S2x': 0.,
+			'S2y': 0.,
+			'S2z': 0.,
+		}
+		parameters['distance'] = 1.e6 * lal.PC_SI
+		parameters['inclination'] = 0.
+		parameters['phiRef'] = 0.
+		parameters['longAscNodes'] = 0.
+		parameters['eccentricity'] = 0.
+		parameters['meanPerAno'] = 0.
+		parameters['deltaF'] = 1.
+		parameters['f_min'] = 10.
+		parameters['f_max'] = 512.
+		parameters['f_ref'] = 0.
+		parameters['LALparams'] = None
+		parameters['approximant'] = lalsim.GetApproximantFromString('IMRPhenomD')
+		try:
+			with error.classify(rules=[error.LAL_RULE_SIM_INPUT_DOMAIN]) as c:
+				_ = lalsim.SimInspiralFD(**parameters)
+		except error.LalSimInputDomainError:
+			assert c.stderr[:10] == 'XLAL Error'
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