perl testing: refactor stand-alone testing into base class (#43044)

lib/spack/docs/build_systems/perlpackage.rst

@@ -173,6 +173,72 @@ arguments to ``Makefile.PL`` or ``Build.PL`` by overriding
        ]
 
 
+^^^^^^^
+Testing
+^^^^^^^
+
+``PerlPackage`` provides a simple stand-alone test of the successfully
+installed package to confirm that installed perl module(s) can be used.
+These tests can be performed any time after the installation using
+``spack -v test run``. (For more information on the command, see 
+:ref:`cmd-spack-test-run`.)
+
+The base class automatically detects perl modules based on the presence
+of ``*.pm`` files under the package's library directory. For example,
+the files under ``perl-bignum``'s perl library are:
+
+.. code-block:: console
+
+   $ find . -name "*.pm"
+   ./bigfloat.pm
+   ./bigrat.pm
+   ./Math/BigFloat/Trace.pm
+   ./Math/BigInt/Trace.pm
+   ./Math/BigRat/Trace.pm
+   ./bigint.pm
+   ./bignum.pm
+
+
+which results in the package having the ``use_modules`` property containing:
+
+.. code-block:: python
+
+   use_modules = [
+       "bigfloat",
+       "bigrat",
+       "Math::BigFloat::Trace",
+       "Math::BigInt::Trace",
+       "Math::BigRat::Trace",
+       "bigint",
+       "bignum",
+   ]
+
+.. note::
+
+   This list can often be used to catch missing dependencies.
+
+If the list is somehow wrong, you can provide the names of the modules
+yourself by overriding ``use_modules`` like so:
+
+ .. code-block:: python
+
+    use_modules = ["bigfloat", "bigrat", "bigint", "bignum"]
+
+If you only want a subset of the automatically detected modules to be
+tested, you could instead define the ``skip_modules`` property on the
+package. So, instead of overriding ``use_modules`` as shown above, you
+could define the following:
+
+ .. code-block:: python
+
+    skip_modules = [
+        "Math::BigFloat::Trace",
+        "Math::BigInt::Trace",
+        "Math::BigRat::Trace",
+    ]
+
+for the same use tests.
+
 ^^^^^^^^^^^^^^^^^^^^^
 Alternatives to Spack
 ^^^^^^^^^^^^^^^^^^^^^

lib/spack/spack/build_systems/perl.py

@@ -4,12 +4,15 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 import inspect
 import os
+from typing import Iterable
 
-from llnl.util.filesystem import filter_file
+from llnl.util.filesystem import filter_file, find
+from llnl.util.lang import memoized
 
 import spack.builder
 import spack.package_base
 from spack.directives import build_system, extends
+from spack.install_test import SkipTest, test_part
 from spack.util.executable import Executable
 
 from ._checks import BaseBuilder, execute_build_time_tests
@@ -28,6 +31,58 @@ class PerlPackage(spack.package_base.PackageBase):
 
     extends("perl", when="build_system=perl")
 
+    @property
+    @memoized
+    def _platform_dir(self):
+        """Name of platform-specific module subdirectory."""
+        perl = self.spec["perl"].command
+        options = "-E", "use Config; say $Config{archname}"
+        out = perl(*options, output=str.split, error=str.split)
+        return out.strip()
+
+    @property
+    def use_modules(self) -> Iterable[str]:
+        """Names of the package's perl modules."""
+        module_files = find(self.prefix.lib, ["*.pm"], recursive=True)
+
+        # Drop the platform directory, if present
+        if self._platform_dir:
+            platform_dir = self._platform_dir + os.sep
+            module_files = [m.replace(platform_dir, "") for m in module_files]
+
+        # Drop the extension and library path
+        prefix = self.prefix.lib + os.sep
+        modules = [os.path.splitext(m)[0].replace(prefix, "") for m in module_files]
+
+        # Drop the perl subdirectory as well
+        return ["::".join(m.split(os.sep)[1:]) for m in modules]
+
+    @property
+    def skip_modules(self) -> Iterable[str]:
+        """Names of modules that should be skipped when running tests.
+
+        These are a subset of use_modules.
+
+        Returns:
+            List of strings of module names.
+        """
+        return []
+
+    def test_use(self):
+        """Test 'use module'"""
+        if not self.use_modules:
+            raise SkipTest("Test requires use_modules package property.")
+
+        perl = self.spec["perl"].command
+        for module in self.use_modules:
+            if module in self.skip_modules:
+                continue
+
+            with test_part(self, f"test_use-{module}", purpose=f"checking use of {module}"):
+                options = ["-we", f'use strict; use {module}; print("OK\n")']
+                out = perl(*options, output=str.split, error=str.split)
+                assert "OK" in out
+
 
 @spack.builder.builder("perl")
 class PerlBuilder(BaseBuilder):
@@ -52,7 +107,7 @@ class PerlBuilder(BaseBuilder):
     phases = ("configure", "build", "install")
 
     #: Names associated with package methods in the old build-system format
-    legacy_methods = ("configure_args", "check")
+    legacy_methods = ("configure_args", "check", "test_use")
 
     #: Names associated with package attributes in the old build-system format
     legacy_attributes = ()

lib/spack/spack/test/cmd/test.py

@@ -221,6 +221,7 @@ def test_test_list_all(mock_packages):
         [
             "fail-test-audit",
             "mpich",
+            "perl-extension",
             "printing-package",
             "py-extension1",
             "py-extension2",