GH-86275: Implementation of hypothesis stubs for property-based tests, with zoneinfo tests (#22863)

These are stubs to be used for adding hypothesis (https://hypothesis.readthedocs.io/en/latest/) tests to the standard library.

When the tests are run in an environment where `hypothesis` and its various dependencies are not installed, the stubs will turn any tests with examples into simple parameterized tests and any tests without examples are skipped.

It also adds hypothesis tests for the `zoneinfo` module, and a Github Actions workflow to run the hypothesis tests as a non-required CI job.

The full hypothesis interface is not stubbed out — missing stubs can be added as necessary.

Co-authored-by: Zac Hatfield-Dodds <zac.hatfield.dodds@gmail.com>

.github/workflows/build.yml

@@ -36,6 +36,7 @@ jobs:
     timeout-minutes: 10
     outputs:
       run_tests: ${{ steps.check.outputs.run_tests }}
+      run_hypothesis: ${{ steps.check.outputs.run_hypothesis }}
     steps:
       - uses: actions/checkout@v3
       - name: Check for source changes
@@ -61,6 +62,17 @@ jobs:
             git diff --name-only origin/$GITHUB_BASE_REF.. | grep -qvE '(\.rst$|^Doc|^Misc)' && echo "run_tests=true" >> $GITHUB_OUTPUT || true
           fi
 
+          # Check if we should run hypothesis tests
+          GIT_BRANCH=${GITHUB_BASE_REF:-${GITHUB_REF#refs/heads/}}
+          echo $GIT_BRANCH
+          if $(echo "$GIT_BRANCH" | grep -q -w '3\.\(8\|9\|10\|11\)'); then
+            echo "Branch too old for hypothesis tests"
+            echo "run_hypothesis=false" >> $GITHUB_OUTPUT
+          else
+            echo "Run hypothesis tests"
+            echo "run_hypothesis=true" >> $GITHUB_OUTPUT
+          fi
+
   check_generated_files:
     name: 'Check if generated files are up to date'
     runs-on: ubuntu-latest
@@ -291,6 +303,90 @@ jobs:
     - name: SSL tests
       run: ./python Lib/test/ssltests.py
 
+  test_hypothesis:
+    name: "Hypothesis Tests on Ubuntu"
+    runs-on: ubuntu-20.04
+    timeout-minutes: 60
+    needs: check_source
+    if: needs.check_source.outputs.run_tests == 'true' && needs.check_source.outputs.run_hypothesis == 'true'
+    env:
+      OPENSSL_VER: 1.1.1t
+      PYTHONSTRICTEXTENSIONBUILD: 1
+    steps:
+    - uses: actions/checkout@v3
+    - name: Register gcc problem matcher
+      run: echo "::add-matcher::.github/problem-matchers/gcc.json"
+    - name: Install Dependencies
+      run: sudo ./.github/workflows/posix-deps-apt.sh
+    - name: Configure OpenSSL env vars
+      run: |
+        echo "MULTISSL_DIR=${GITHUB_WORKSPACE}/multissl" >> $GITHUB_ENV
+        echo "OPENSSL_DIR=${GITHUB_WORKSPACE}/multissl/openssl/${OPENSSL_VER}" >> $GITHUB_ENV
+        echo "LD_LIBRARY_PATH=${GITHUB_WORKSPACE}/multissl/openssl/${OPENSSL_VER}/lib" >> $GITHUB_ENV
+    - name: 'Restore OpenSSL build'
+      id: cache-openssl
+      uses: actions/cache@v3
+      with:
+        path: ./multissl/openssl/${{ env.OPENSSL_VER }}
+        key: ${{ runner.os }}-multissl-openssl-${{ env.OPENSSL_VER }}
+    - name: Install OpenSSL
+      if: steps.cache-openssl.outputs.cache-hit != 'true'
+      run: python3 Tools/ssl/multissltests.py --steps=library --base-directory $MULTISSL_DIR --openssl $OPENSSL_VER --system Linux
+    - name: Add ccache to PATH
+      run: |
+        echo "PATH=/usr/lib/ccache:$PATH" >> $GITHUB_ENV
+    - name: Configure ccache action
+      uses: hendrikmuhs/ccache-action@v1.2
+    - name: Setup directory envs for out-of-tree builds
+      run: |
+        echo "CPYTHON_RO_SRCDIR=$(realpath -m ${GITHUB_WORKSPACE}/../cpython-ro-srcdir)" >> $GITHUB_ENV
+        echo "CPYTHON_BUILDDIR=$(realpath -m ${GITHUB_WORKSPACE}/../cpython-builddir)" >> $GITHUB_ENV
+    - name: Create directories for read-only out-of-tree builds
+      run: mkdir -p $CPYTHON_RO_SRCDIR $CPYTHON_BUILDDIR
+    - name: Bind mount sources read-only
+      run: sudo mount --bind -o ro $GITHUB_WORKSPACE $CPYTHON_RO_SRCDIR
+    - name: Configure CPython out-of-tree
+      working-directory: ${{ env.CPYTHON_BUILDDIR }}
+      run: ../cpython-ro-srcdir/configure --with-pydebug --with-openssl=$OPENSSL_DIR
+    - name: Build CPython out-of-tree
+      working-directory: ${{ env.CPYTHON_BUILDDIR }}
+      run: make -j4
+    - name: Display build info
+      working-directory: ${{ env.CPYTHON_BUILDDIR }}
+      run: make pythoninfo
+    - name: Remount sources writable for tests
+      # some tests write to srcdir, lack of pyc files slows down testing
+      run: sudo mount $CPYTHON_RO_SRCDIR -oremount,rw
+    - name: Setup directory envs for out-of-tree builds
+      run: |
+        echo "CPYTHON_BUILDDIR=$(realpath -m ${GITHUB_WORKSPACE}/../cpython-builddir)" >> $GITHUB_ENV
+    - name: "Create hypothesis venv"
+      working-directory: ${{ env.CPYTHON_BUILDDIR }}
+      run: |
+        VENV_LOC=$(realpath -m .)/hypovenv
+        VENV_PYTHON=$VENV_LOC/bin/python
+        echo "HYPOVENV=${VENV_LOC}" >> $GITHUB_ENV
+        echo "VENV_PYTHON=${VENV_PYTHON}" >> $GITHUB_ENV
+        ./python -m venv $VENV_LOC && $VENV_PYTHON -m pip install -U hypothesis
+    - name: "Run tests"
+      working-directory: ${{ env.CPYTHON_BUILDDIR }}
+      run: |
+        # Most of the excluded tests are slow test suites with no property tests
+        #
+        # (GH-104097) test_sysconfig is skipped because it has tests that are
+        # failing when executed from inside a virtual environment.
+        ${{ env.VENV_PYTHON }} -m test \
+          -W \
+          -x test_asyncio \
+          -x test_multiprocessing_fork \
+          -x test_multiprocessing_forkserver \
+          -x test_multiprocessing_spawn \
+          -x test_concurrent_futures \
+          -x test_socket \
+          -x test_subprocess \
+          -x test_signal \
+          -x test_sysconfig
+
 
   build_asan:
     name: 'Address sanitizer'