extend black formatting to tests as well

.pre-commit-config.yaml

@@ -1,14 +1,12 @@
-exclude: ^tests/fixtures/example-code/
+exclude: ^tests/fixtures/
 repos:
 -   repo: https://github.com/pre-commit/pre-commit-hooks
     rev: v3.4.0
     hooks:
     -   id: check-yaml
     -   id: debug-statements
-        exclude: ^tests/fixtures/example-code/invalid-syntax.py$
     -   id: end-of-file-fixer
     -   id: trailing-whitespace
-        exclude: ^tests/fixtures/diffs/
 -   repo: https://github.com/asottile/reorder_python_imports
     rev: v2.4.0
     hooks:
@@ -18,8 +16,7 @@ repos:
     rev: 20.8b1
     hooks:
     -   id: black
-        args: [--line-length=78]
-        files: ^src/
+        args: [--line-length=79]
 -   repo: https://github.com/asottile/pyupgrade
     rev: v2.12.0
     hooks:
@@ -29,4 +26,4 @@ repos:
     rev: v0.812
     hooks:
     -   id: mypy
-        exclude: ^(docs/|example-plugin/|tests/fixtures)
+        exclude: ^(docs/|example-plugin/)