Adds a test to ensure the parameter n_iter_without_progress is used correctly

Sebastian Saeger · Sebastian Saeger · commit 2d41da7a1f5d · 2016-03-07T00:21:57.000+01:00
diff --git a/sklearn/manifold/tests/test_t_sne.py b/sklearn/manifold/tests/test_t_sne.py
@@ -542,3 +542,24 @@ def test_index_offset():
     # Make sure translating between 1D and N-D indices are preserved
     assert_equal(_barnes_hut_tsne.test_index2offset(), 1)
     assert_equal(_barnes_hut_tsne.test_index_offset(), 1)
+
+
+def test_n_iter_without_progress():
+    # Make sure that the parameter n_iter_without_progress is used correctly
+    random_state = check_random_state(0)
+    X = random_state.randn(100, 2)
+    tsne = TSNE(n_iter_without_progress=2, verbose=2,
+                random_state=0, method='exact')
+
+    old_stdout = sys.stdout
+    sys.stdout = StringIO()
+    try:
+        tsne.fit_transform(X)
+    finally:
+        out = sys.stdout.getvalue()
+        sys.stdout.close()
+        sys.stdout = old_stdout
+
+    # The output needs to contain the value of n_iter_without_progress
+    assert("did not make any progress during the "
+           "last 2 episodes. Finished." in out)
