fixed logger tests.

zipline/utils/logger.py

@@ -3,6 +3,7 @@ Small classes to assist with timezone calculations, LOGGER configuration,
 and other common operations.
 """
 
+
 import logging
 import logging.config
 from os.path import join, abspath, dirname
@@ -17,3 +18,34 @@ def logger_path():
     import zipline
     log_path = dirname(abspath(zipline.__file__))
     return join(log_path, 'logging.cfg')
+
+
+# utility for tailing a log file.
+def tail( f, window=20 ):
+    """
+    from
+    http://stackoverflow.com/questions/136168/get-last-n-lines-of-a-file- \
+            with-python-similar-to-tail
+    """
+    BUFSIZ = 1024
+    f.seek(0, 2)
+    bytes = f.tell()
+    size = window
+    block = -1
+    data = []
+    while size > 0 and bytes > 0:
+        if (bytes - BUFSIZ > 0):
+            # Seek back one whole BUFSIZ
+            f.seek(block*BUFSIZ, 2)
+            # read BUFFER
+            data.append(f.read(BUFSIZ))
+        else:
+            # file too small, start from begining
+            f.seek(0,0)
+            # only read what was not read
+            data.append(f.read(bytes))
+        linesFound = data[-1].count('\n')
+        size -= linesFound
+        bytes -= BUFSIZ
+        block -= 1
+    return '\n'.join(''.join(data).splitlines()[-window:])