Modernize code to Python 3.6+ (#1229)

1. `class A(object)` can be written as `class A:`
2. replace `dict([…])` and `set([…])` with `{…}`
3. use f-strings or compact `.format`
4. use `yield from` instead of `yield` in a `for` loop
5. import `mock` from `unittest`
6. expect `OSError` instead of `IOError` or `select` error
7. use Python3 defaults for file reading or `super()`
8. remove redundant parenthesis (keep those in tuples though)
9. shorten set intersection instead of creating lists
10. backslashes in strings do not have to be escaped if prepended with `r`

1 files changed, 3 insertions, 3 deletions

diff --git a/tests/test_smart_completion_public_schema_only.py b/tests/test_smart_completion_public_schema_only.py
index b9357092..db1fe0a3 100644
--- a/tests/test_smart_completion_public_schema_only.py
+++ b/tests/test_smart_completion_public_schema_only.py
@@ -53,7 +53,7 @@ metadata = {
     ],
 }
 
-metadata = dict((k, {"public": v}) for k, v in metadata.items())
+metadata = {k: {"public": v} for k, v in metadata.items()}
 
 testdata = MetaData(metadata)
 
@@ -296,7 +296,7 @@ def test_suggested_cased_always_qualified_column_names(completer):
 def test_suggested_column_names_in_function(completer):
     result = get_result(completer, "SELECT MAX( from users", len("SELECT MAX("))
     assert completions_to_set(result) == completions_to_set(
-        (testdata.columns_functions_and_keywords("users"))
+        testdata.columns_functions_and_keywords("users")
     )
 
 
@@ -316,7 +316,7 @@ def test_suggested_column_names_with_alias(completer):
 def test_suggested_multiple_column_names(completer):
     result = get_result(completer, "SELECT id,  from users u", len("SELECT id, "))
     assert completions_to_set(result) == completions_to_set(
-        (testdata.columns_functions_and_keywords("users"))
+        testdata.columns_functions_and_keywords("users")
     )