* Add tests for is_number

tests/test_number.py

@@ -0,0 +1,34 @@
+from spacy.orth import is_number
+
+
+def test_digits():
+    assert is_number('10')
+    assert is_number('1')
+
+
+def test_comma():
+    assert is_number('10,000')
+    assert is_number('10,00')
+    assert is_number(',10')
+
+
+def test_period():
+    assert is_number('999.0')
+    assert is_number('.99')
+
+
+def test_fraction():
+    assert is_number('1/2')
+    assert not is_number('1/2/3')
+
+
+def test_word():
+    assert is_number('one')
+    assert is_number('two')
+    assert is_number('billion')
+
+
+def test_not_number():
+    assert not is_number('dog')
+    assert not is_number(',')
+