TEST: Add tests for compute_fp.py (QuantEcon#309)

* TEST: Add tests for compute_fp.py

* TEST: Add `show_missing = True` to coveragerc

http://stackoverflow.com/questions/37733194/python-nosetests-with-coverage-no-longer-shows-missing-lines

* TEST: Add `# pragma: no cover`

Author: oyamad

.coveragerc

@@ -9,6 +9,7 @@ omit =
     */unittest2/*
 
 [report]
+show_missing = True
 # Regexes for lines to exclude from consideration
 exclude_lines =
     # Have to re-enable the standard pragma

quantecon/compute_fp.py

@@ -364,7 +364,7 @@ def _square_sum(a):
         return _square_sum_array
 
 
-def _square_sum_array(a):
+def _square_sum_array(a):  # pragma: no cover
     sum_ = 0
     for x in a.flat:
         sum_ += x**2

quantecon/tests/test_compute_fp.py

@@ -15,6 +15,7 @@
 from __future__ import division
 import unittest
 import numpy as np
+from nose.tools import ok_, raises
 from quantecon import compute_fixed_point
 
 
@@ -91,3 +92,53 @@ def test_imitation_game_method(self):
                 abs(self.T(fp_computed, mu=mu) - fp_computed).max() <=
                 error_tol
             )
+
+
+class TestComputeFPContraction():
+    def setUp(self):
+        self.coeff = 0.5
+        self.methods = ['iteration', 'imitation_game']
+
+    def f(self, x):
+        return self.coeff * x
+
+    def test_num_iter_one(self):
+        init = 1.
+        error_tol = self.coeff
+
+        for method in self.methods:
+            fp_computed = compute_fixed_point(self.f, init,
+                                              error_tol=error_tol,
+                                              method=method)
+            ok_(fp_computed <= error_tol * 2)
+
+    def test_num_iter_large(self):
+        init = 1.
+        buff_size = 2**8  # buff_size in 'imitation_game'
+        max_iter = buff_size + 2
+        error_tol = self.coeff**max_iter
+
+        for method in self.methods:
+            fp_computed = compute_fixed_point(self.f, init,
+                                              error_tol=error_tol,
+                                              max_iter=max_iter, method=method,
+                                              print_skip=max_iter)
+            ok_(fp_computed <= error_tol * 2)
+
+    def test_2d_input(self):
+        error_tol = self.coeff**4
+
+        for method in self.methods:
+            init = np.array([[-1, 0.5], [-1/3, 0.1]])
+            fp_computed = compute_fixed_point(self.f, init,
+                                              error_tol=error_tol,
+                                              method=method)
+            ok_((fp_computed <= error_tol * 2).all())
+
+
+@raises(ValueError)
+def test_raises_value_error_nonpositive_max_iter():
+    f = lambda x: 0.5*x
+    init = 1.
+    max_iter = 0
+    fp = compute_fixed_point(f, init, max_iter=max_iter)