Test repo_helper's experimental build backend.

Author: domdfcoding

.travis.yml

@@ -31,7 +31,6 @@ stages:
   - deploy_pypi
   - deploy_conda
 
-
 jobs:
   allow_failures:
     - arch: arm64

pyproject.toml

@@ -1,3 +1,3 @@
 [build-system]
-requires = ["setuptools>=40.6.0", "wheel>=0.34.2"]
-build-backend = "setuptools.build_meta"
+requires = ["repo-helper", "setuptools>=40.6.0", "wheel>=0.34.2"]
+build-backend = "repo_helper.build"

repo_helper.yml

@@ -12,6 +12,7 @@ python_versions:
  - "3.8"
  - "pypy3"
  - "3.9"
+ - "3.9-dev"
 
 # travis secure password for PyPI
 travis_pypi_secure: "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"
@@ -61,3 +62,5 @@ intersphinx_mapping:
 
 mypy_deps:
  - pprint36
+
+use_experimental_backend: true

tox.ini

@@ -110,9 +110,9 @@ commands = yapf -i --recursive domdf_python_tools tests --exclude "*.pyi"
 
 [testenv:mypy]
 basepython = python3.6
-extras = all
 ignore_errors = True
 changedir = {toxinidir}
+extras = all
 deps =
     mypy==0.790
     lxml