gh-149640: Add new GitHub action to test lazy_imports=all against test suite

.github/workflows/build.yml

@@ -496,6 +496,12 @@ jobs:
         name: hypothesis-example-db
         path: ${{ env.CPYTHON_BUILDDIR }}/.hypothesis/examples/
 
+  test-lazy-imports-all:
+    name: 'Lazy Imports All Enabled'
+    needs: build-context
+    if: fromJSON(needs.build-context.outputs.run-tests)
+    uses: ./.github/workflows/reusable-test-lazy-imports-all.yml
+
   build-asan:
     name: 'Address sanitizer'
     runs-on: ${{ matrix.os }}
@@ -669,6 +675,7 @@ jobs:
     - build-emscripten
     - build-wasi
     - test-hypothesis
+    - test-lazy-imports-all
     - build-asan
     - build-san
     - cross-build-linux

.github/workflows/reusable-test-lazy-imports-all.yml

@@ -0,0 +1,63 @@
+name: Reusable Lazy Imports Tests
+
+# Run the CPython test suite with global lazy imports forced on
+# (``PYTHON_LAZY_IMPORTS=all``, equivalent to ``-X lazy_imports=all``).
+#
+# Modules that are known to fail under lazy imports are listed in
+# Lib/test/lazy_imports_all_exclude.txt and skipped here. Remove entries from
+# that file as the modules are fixed so this workflow starts guarding them
+# against regressions.
+
+on:
+  workflow_call:
+
+permissions:
+  contents: read
+
+env:
+  FORCE_COLOR: 1
+
+jobs:
+  test-lazy-imports-all:
+    name: 'Lazy Imports All Enabled'
+    runs-on: ubuntu-24.04
+    timeout-minutes: 60
+    env:
+      PYTHON_LAZY_IMPORTS: all
+      EXCLUDE_FILE: Lib/test/lazy_imports_all_exclude.txt
+    steps:
+    - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+      with:
+        persist-credentials: false
+    - 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 CPython
+      run: ./configure --config-cache --with-pydebug
+    - name: Build CPython
+      run: make -j4
+    - name: Display build info
+      run: make pythoninfo
+    - name: Verify lazy imports are fullly enabled
+      run: ./python -c "import sys; assert sys.flags.lazy_imports == 1, sys.flags.lazy_imports; print('lazy imports all enabled')"
+    - name: Build test list (all tests minus the known-failing exclusions)
+      run: |
+        set -euo pipefail
+        ./python -m test --list-tests > all_tests.txt
+        # Strip comments/blank lines from the exclusion file, then drop those
+        # exact test names (whole-line, fixed-string match) from the run list.
+        grep -vE '^\s*(#.*)?$' "$EXCLUDE_FILE" > exclude_tests.txt
+        grep -vxF -f exclude_tests.txt all_tests.txt > run_tests.txt
+        # Fail loudly if any exclusion entry matched nothing: a stale or
+        # mistyped name (or a change in `--list-tests` output) would otherwise
+        # silently stop excluding a module and let it fail the run.
+        stale=$(comm -23 <(sort -u exclude_tests.txt) <(sort -u all_tests.txt))
+        if [ -n "$stale" ]; then
+          echo "::error::Stale entries in $EXCLUDE_FILE (no longer match 'python -m test --list-tests'); remove or fix them:"
+          echo "$stale"
+          exit 1
+        fi
+        echo "Excluding $(wc -l < exclude_tests.txt) module(s); running $(wc -l < run_tests.txt) of $(wc -l < all_tests.txt)."
+    - name: Run stdlib tests with lazy imports
+      run: xvfb-run xargs ./python -m test --fast-ci --timeout=900 < run_tests.txt

Lib/test/lazy_imports_all_exclude.txt

@@ -0,0 +1,41 @@
+# Test modules that currently FAIL under global lazy imports
+# (``-X lazy_imports=all`` / ``PYTHON_LAZY_IMPORTS=all``).
+#
+# The "Lazy Imports All" CI workflow (.github/workflows/lazy-imports-all.yml) runs the
+# whole test suite with lazy_imports=all, skipping every module listed
+# here. Exclusion is whole-module: a listed module is skipped entirely, so any
+# passing tests it contains are not covered until its line is removed. As each
+# module is fixed, delete its line so the workflow starts guarding it against
+# regressions.
+#
+# Format: one test name per line, exactly as printed by
+# ``python -m test --list-tests``. Lines starting with ``#`` and blank lines
+# are ignored. Note that split test packages use a dotted path
+# (e.g. test.test_future_stmt.test_future) while ordinary modules use the bare
+# name (e.g. test_builtin).
+
+test.test_inspect.test_inspect
+test.test_pydoc.test_pydoc
+test___all__
+test__interpreters
+test_builtin
+test_clinic
+test_compileall
+test_crossinterp
+test_datetime
+test_external_inspection
+test_generated_cases
+test_idle
+test_import
+test_importlib
+test_interpreters
+test_json
+test_lazy_import
+test_subprocess
+test_symtable
+test_tools
+test_trace
+test_typing
+test_unittest
+test_xmlrpc
+test_zipfile