specific line-length in pyproject.toml rather on command line arguments.

Author: WindSoilder

ci/travis.sh

@@ -55,15 +55,15 @@ pip install -U pip setuptools wheel
 
 if [ "$CHECK_FORMATTING" = "1" ]; then
     pip install black
-    if ! black --check --diff -l 79 setup.py exceptiongroup; then
+    if ! black --check --diff setup.py exceptiongroup; then
         cat <<EOF
 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
 Formatting problems were found (listed above). To fix them, run
 
    pip install black
-   black -l 79 setup.py exceptiongroup
+   black setup.py exceptiongroup
 
 in your local checkout.
 

pyproject.toml

@@ -4,3 +4,6 @@ filename = "docs/source/history.rst"
 directory = "newsfragments"
 underlines = ["-", "~", "^"]
 issue_format = "`#{issue} <https://github.com/python-trio/exceptiongroup/issues/{issue}>`__"
+
+[tool.black]
+line-length = 79