Add two more test cases for string compress coding challenge. (#125)

* Add two more test cases for string compress coding challenge.

I believe that the existing test cases are not strict enough to assure
a proper solution for this challenge.

I was able to implement a wrong, but still passing solution to this
basing on set and collections.Counter mechanism, since the test cases
present only situations with singular occurrences of a letter chain and
all the test strings are alphabetically sorted.

I believe that the two new test cases enforce more thorough approach to
the problem and, in effect, the test cases are more descriptive.

* Fix the results in tests since the solution changed in the meantine on
original branch.

* Update also the test_compress and solution.

arrays_strings/compress/compress_challenge.ipynb

@@ -123,6 +123,8 @@
     "        assert_equal(func(''), '')\n",
     "        assert_equal(func('AABBCC'), 'AABBCC')\n",
     "        assert_equal(func('AAABCCDDDDE'), 'A3BC2D4E')\n",
+    "        assert_equal(func('BAAACCDDDD'), 'BA3C2D4')\n",
+    "        assert_equal(func('AAABAACCDDDD'), 'A3BA2C2D4')\n",
     "        print('Success: test_compress')\n",
     "\n",
     "\n",

arrays_strings/compress/compress_solution.ipynb

@@ -153,6 +153,8 @@
     "        assert_equal(func(''), '')\n",
     "        assert_equal(func('AABBCC'), 'AABBCC')\n",
     "        assert_equal(func('AAABCCDDDDE'), 'A3BC2D4E')\n",
+    "        assert_equal(func('BAAACCDDDD'), 'BA3C2D4')\n",
+    "        assert_equal(func('AAABAACCDDDD'), 'A3BA2C2D4')\n",
     "        print('Success: test_compress')\n",
     "\n",
     "\n",

arrays_strings/compress/test_compress.py

@@ -8,6 +8,8 @@ class TestCompress(object):
         assert_equal(func(''), '')
         assert_equal(func('AABBCC'), 'AABBCC')
         assert_equal(func('AAABCCDDDDE'), 'A3BC2D4E')
+        assert_equal(func('BAAACCDDDD'), 'BA3C2D4')
+        assert_equal(func('AAABAACCDDDD'), 'A3BA2C2D4')
         print('Success: test_compress')