From 2587cd65128d4aea7e417692a1b456ac60f0043a Mon Sep 17 00:00:00 2001
From: Eddie Hebert <ehebert@quantopian.com>
Date: Wed, 30 Jan 2013 14:04:17 -0500
Subject: [PATCH] Enriches message returned for test batch transform.

Adds formatting of the failing values when ReturnPriceBatchTransform's
data shape does not match the window_length.
---
 zipline/test_algorithms.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/zipline/test_algorithms.py b/zipline/test_algorithms.py
index b22d2719..e86e1a21 100644
--- a/zipline/test_algorithms.py
+++ b/zipline/test_algorithms.py
@@ -237,7 +237,9 @@ class TestRegisterTransformAlgorithm(TradingAlgorithm):
 
 class ReturnPriceBatchTransform(BatchTransform):
     def get_value(self, data):
-        assert data.shape[1] == self.window_length
+        assert data.shape[1] == self.window_length, \
+            "data shape={0} does not equal window_length={1} for data={2}".\
+            format(data.shape[1], self.window_length, data)
         return data.price