Replace requirements.txt with extras_require

Makefile

@@ -39,7 +39,6 @@ help:
 	@echo "  inplace            make inplace extension"
 	@echo "  install            make and install"
 	@echo "  install-coverage   make and install with C coverage"
-	@echo "  install-req        install documentation and test dependencies"
 	@echo "  install-venv       (deprecated) install in virtualenv"
 	@echo "  lint               run the lint checks"
 	@echo "  lint-fix           run black and isort to (mostly) fix lint issues."
@@ -70,20 +69,14 @@ debug:
 	make clean > /dev/null
 	CFLAGS='-g -O0' python3 -m pip install --global-option="build_ext" . > /dev/null
 
-.PHONY: install-req
-install-req:
-	python3 -m pip install -r requirements.txt
-
 .PHONY: install-venv
 install-venv:
 	echo "'install-venv' is deprecated and will be removed in a future Pillow release"
 	virtualenv .
-	bin/pip install -r requirements.txt
 
 .PHONY: release-test
 release-test:
-	$(MAKE) install-req
-	python3 -m pip install -e .
+	python3 -m pip install -e .[tests]
 	python3 selftest.py
 	python3 -m pytest Tests
 	python3 -m pip install .

docs/reference/c_extension_debugging.rst

@@ -53,7 +53,7 @@ Then ``sudo apt-get update && sudo apt-get install libtiff5-dbgsym``
 
     virtualenv -p python3.8-dbg ~/vpy38-dbg
     source ~/vpy38-dbg/bin/activate
-    cd ~/Pillow && pip install -r requirements.txt && make install
+    cd ~/Pillow && make install
 
 Test Case
 ---------

requirements.txt

@@ -1,18 +0,0 @@
-# Development, documentation & testing requirements.
-black
-check-manifest
-coverage
-defusedxml
-markdown2
-olefile
-packaging
-pyroma
-pytest
-pytest-cov
-pytest-timeout
-sphinx>=2.4
-sphinx-copybutton
-sphinx-issues>=3.0.1
-sphinx-removed-in
-sphinx-rtd-theme>=1.0
-sphinxext-opengraph

setup.cfg

@@ -35,6 +35,26 @@ project_urls =
 [options]
 python_requires = >=3.7
 
+[options.extras_require]
+docs =
+    sphinx>=2.4
+    sphinx-copybutton
+    sphinx-issues>=3.0.1
+    sphinx-removed-in
+    sphinx-rtd-theme>=1.0
+    sphinxext-opengraph
+tests =
+    check-manifest
+    coverage
+    defusedxml
+    markdown2
+    olefile
+    packaging
+    pyroma
+    pytest
+    pytest-cov
+    pytest-timeout
+
 [flake8]
 extend-ignore = E203
 max-line-length = 88

tox.ini

@@ -10,6 +10,8 @@ envlist =
 minversion = 1.9
 
 [testenv]
+extras =
+    tests
 commands =
     make clean
     {envpython} -m pip install --global-option="build_ext" --global-option="--inplace" .
@@ -18,9 +20,6 @@ commands =
 deps =
     cffi
     numpy
-    olefile
-    pyroma
-    pytest
 
 [testenv:lint]
 commands =