bf: add 100% line coverage test

plugins/bf.py

@@ -3,16 +3,13 @@ http://brainfuck.sourceforge.net/brain.py'''
 
 import re
 import random
+import unittest
 
 from util import hook
 
 
-BUFFER_SIZE = 5000
-MAX_STEPS = 1000000
-
-
 @hook.command
-def bf(inp):
+def bf(inp, max_steps=1000000, buffer_size=5000):
     ".bf <prog> -- executes brainfuck program <prog>"""
 
     program = re.sub('[^][<>+-.,]', '', inp)
@@ -37,7 +34,7 @@ def bf(inp):
     ip = 0        # instruction pointer
     mp = 0        # memory pointer
     steps = 0
-    memory = [0] * BUFFER_SIZE  # initial memory area
+    memory = [0] * buffer_size  # initial memory area
     rightmost = 0
     output = ""   # we'll save the output here
 
@@ -54,9 +51,9 @@ def bf(inp):
                 rightmost = mp
                 if mp >= len(memory):
                     # no restriction on memory growth!
-                    memory.extend([0] * BUFFER_SIZE)
+                    memory.extend([0] * buffer_size)
         elif c == '<':
-            mp = mp - 1 % len(memory)
+            mp = (mp - 1) % len(memory)
         elif c == '.':
             output += chr(memory[mp])
             if len(output) > 500:
@@ -72,10 +69,10 @@ def bf(inp):
 
         ip += 1
         steps += 1
-        if steps > MAX_STEPS:
+        if steps > max_steps:
             if output == '':
-                output = '(no output)'
-            output += '[exceeded %d iterations]' % MAX_STEPS
+                output = 'no output'
+            output += ' [exceeded %d iterations]' % max_steps
             break
 
     stripped_output = re.sub(r'[\x00-\x1F]', '', output)
@@ -86,3 +83,37 @@ def bf(inp):
         return 'no output'
 
     return stripped_output[:430].decode('utf8', 'ignore')
+
+
+class BFTest(unittest.TestCase):
+    def test_hello(self):
+        assert bf('--[>--->->->++>-<<<<<-------]>--.>---------.>--..+++.>---'
+                  '-.>+++++++++.<<.+++.------.<-.>>+.') == 'Hello world!'
+
+    def test_unbalanced(self):
+        assert 'unbalanced' in bf('[[++]]]')
+        assert 'unbalanced' in bf('[[[++]]')
+
+    def test_comment(self):
+        assert bf('[this is a comment!]++++++[>+++++++<-]>.') == '*'
+
+    def test_unprintable(self):
+        assert bf('+.') == 'no printable output'
+
+    def test_empty(self):
+        assert bf('+++[-]') == 'no output'
+
+    def test_exceeded(self):
+        assert bf('+[>,[-]<]', 1000) == 'no output [exceeded 1000 iterations]'
+
+    def test_inf_mem(self):
+        assert 'no output [exceeded 1000 iterations]' == \
+            bf('+[>[.-]+]', 1000, buffer_size=10)
+
+    def test_left_wrap(self):
+        # eventually, wrap around and hit ourselves
+        assert 'aaaa' in bf('+[<[-' + '+' * ord('a') + '.[-]]+]',
+                            2000, buffer_size=5)
+
+    def test_too_much_output(self):
+        assert 'a' * 430 == bf('+' * ord('a') + '[.]')