Add test-release script & makefile target

Running the script sends the already built package to
test pypi, then uses pip to download and install it from
there, and does a minimal invocation of the installed
package. If the package has not been built correctly,
this might detect some errors before we send it to
the real pypi.

Makefile

@@ -5,6 +5,7 @@
 # with Cygwin binaries at the start of the PATH.
 
 NAME=colorama
+SHELL=/bin/bash
 
 help: ## Display help for documented make targets.
 	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | \
@@ -18,6 +19,7 @@ pip=$(virtualenv)/bin/pip
 syspython=python3.8
 python=$(virtualenv)/bin/python
 twine=$(virtualenv)/bin/twine
+version=$(shell $(python) setup.py --version)
 
 clean: ## Remove build artifacts, .pyc files, virtualenv
 	-rm -rf build dist MANIFEST colorama.egg-info $(virtualenv)
@@ -48,11 +50,16 @@ test: ## Run tests
 
 # build packages
 
-build: clean ## Build an sdist and wheel
+build: ## Build an sdist and wheel
+	$(python) -m pip install --upgrade setuptools wheel
 	$(python) setup.py sdist bdist_wheel
 .PHONY: sdist
 
+test-release: build
+	./test-release
+.PHONY: test-release
+
 upload: ## Upload our sdist and wheel
-	$(twine) upload dist/*
+	$(twine) upload dist/colorama-$(version)-*
 .PHONY: release
 

test-release

@@ -0,0 +1,42 @@
+#/usr/bin/env bash
+
+# Test the currently built release of Colorama from the dist/ dir.
+# Run this before making a release.
+#
+# This should be run on Windows, because Colorama is mostly a no-op elsewhere.
+# Hmmm, this script should probably be a .bat file then? Nah, WSL FTW.
+#
+# Uploads package from the dist/ directory to the *test* PyPI.
+# Create a fresh virtualenvironment and install colorama from test PyPI.
+# Import Colorama and make trivial use of it.
+
+# Exit on error
+set -eu -o pipefail
+
+syspython=python3.8
+bin="$HOME/.virtualenvs/colorama/bin"
+version=$($bin/python setup.py --version)
+sandbox=test-release-playground
+
+# Upload to the test pypi.
+$bin/twine upload --repository testpypi dist/colorama-$version-* \
+    || echo "  > Expect a 400 if package was already uploaded."
+
+# cd elsewhere so we cannot import from local source.
+mkdir -p $sandbox
+(
+    cd $sandbox
+
+    # Create a new virtualenv
+    $syspython -m venv --clear venv
+
+    # Install the package we just uploaded
+    venv/bin/python -m pip --quiet install --index-url https://test.pypi.org/simple colorama==$version
+
+    # Test the package can be imported
+    venv/bin/python -c "import colorama; colorama.init(); print(colorama.Fore.GREEN + \"OK: Colorama\", colorama.__version__, \"from test pypi install.\")"
+)
+
+# Tidy up
+rm -rf $sandbox
+