test_url_query: Add tests for double-decoding of query values

Add test for the problem we're trying to solve in encoding and decoding
query values. (aio-libsGH-210)

Also drop FIXME for the case of `a` vs `a=` in query string, as we don't
have plans to differentiate beetween them for the time being.

tests/test_url_query.py

@@ -12,8 +12,6 @@
 # ========================================
 
 URLS_WITH_BASIC_QUERY_VALUES = [
-
-    # Empty strings, keys and values
     (
         URL('http://example.com'),
         MultiDict(),
@@ -26,8 +24,9 @@
         URL('http://example.com?a='),
         MultiDict([('a', '')]),
     ),
+]  # type: List[Tuple[URL, MultiDict]]
 
-    # ASCII chars
+URLS_WITH_ASCII_QUERY_VALUES = [
     (
         # TODO: Double check if key is expected as `a b` or `a+b`.
         URL('http://example.com?a+b=c+d'),
@@ -41,8 +40,10 @@
         URL('http://example.com?a=1&b=2&a=3'),
         MultiDict([('a', '1'), ('b', '2'), ('a', '3')]),
     ),
+]  # type: List[Tuple[URL, MultiDict]]
 
-    # Non-ASCI BMP chars
+URLS_WITH_NON_ASCII_QUERY_VALUES = [
+    # BMP chars
     (
         URL('http://example.com?ключ=знач'),
         MultiDict({'ключ': 'знач'}),
@@ -62,7 +63,9 @@
 
 @pytest.mark.parametrize(
     'original_url, expected_query',
-    URLS_WITH_BASIC_QUERY_VALUES,
+    URLS_WITH_BASIC_QUERY_VALUES
+    + URLS_WITH_ASCII_QUERY_VALUES
+    + URLS_WITH_NON_ASCII_QUERY_VALUES,
 )
 def test_query_basic_parsing(original_url, expected_query):
     assert isinstance(original_url.query, MultiDictProxy)
@@ -71,13 +74,11 @@ def test_query_basic_parsing(original_url, expected_query):
 
 @pytest.mark.parametrize(
     'original_url, expected_query',
-    URLS_WITH_BASIC_QUERY_VALUES,
+    URLS_WITH_ASCII_QUERY_VALUES + URLS_WITH_NON_ASCII_QUERY_VALUES,
 )
 def test_query_basic_update_query(original_url, expected_query):
     new_url = original_url.update_query({})
-    # FIXME: `?a` becomes `?a=` right now. Maybe support `None` values?
-    # assert new_url == original_url
-    assert new_url is not None
+    assert new_url == original_url
 
 
 def test_query_dont_unqoute_twice():
@@ -167,3 +168,51 @@ def test_query_from_empty_update_query(
 
     # FIXME: Broken because of asymmetric query encoding
     # assert new_url == original_url
+
+
+# ========================================
+# Setting and getting query values
+# ========================================
+
+def test_query_set_encoded_url_as_value():
+    original_url = URL('http://example.com')
+
+    new_url_1 = original_url.update_query({'foo': '𝕦𝕟𝕚'})
+    assert '𝕦𝕟𝕚' == new_url_1.query['foo']
+
+    new_url_1_str = str(new_url_1)
+    assert (
+        'http://example.com/?foo=%F0%9D%95%A6%F0%9D%95%9F%F0%9D%95%9A'
+    ) == new_url_1_str
+
+    new_url_2 = original_url.update_query({'bar': new_url_1_str})
+    # FIXME: Double-decoding query value
+    # assert new_url_1_str == new_url_2.query['bar']
+    assert 'http://example.com/?foo=𝕦𝕟𝕚' == new_url_2.query['bar']
+
+    new_url_2_str = str(new_url_2)
+    # FIXME: Double-decoding query value
+    # assert (
+    #     'http://example.com/?bar=http%3A//example.com/%3Ffoo%3D'
+    #     '%25F0%259D%2595%25A6%25F0%259D%2595%259F%25F0%259D%2595%259A'
+    # ) == new_url_2_str
+    assert (
+        'http://example.com/?bar=http://example.com/?foo%3D'
+        '%F0%9D%95%A6%F0%9D%95%9F%F0%9D%95%9A'
+    ) == new_url_2_str
+
+    new_url_3 = original_url.with_query({'bar': new_url_1_str})
+    # FIXME: Double-decoding query value
+    # assert new_url_1_str == new_url_3.query['bar']
+    assert 'http://example.com/?foo=𝕦𝕟𝕚' == new_url_3.query['bar']
+
+    new_url_3_str = str(new_url_3)
+    # FIXME: Double-decoding query value
+    # assert (
+    #     'http://example.com/?bar=http%3A//example.com/%3Ffoo%3D'
+    #     '%25F0%259D%2595%25A6%25F0%259D%2595%259F%25F0%259D%2595%259A'
+    # ) == new_url_3_str
+    assert (
+        'http://example.com/?bar=http://example.com/?foo%3D'
+        '%F0%9D%95%A6%F0%9D%95%9F%F0%9D%95%9A'
+    ) == new_url_3_str