Add scratch module roots to test configuration (#19477)

fixes #19476

Module file content is written to file in a
temporary location and read back to be analyzed
by unit tests.

The approach to patch "open" and write to a
StringIO in memory has been abandoned, since
over time other operations insisting on the
filesystem have been added to the module file
generator.

4 files changed, 23 insertions, 82 deletions

diff --git a/lib/spack/spack/test/conftest.py b/lib/spack/spack/test/conftest.py
index 152c2c846e..0a39d1c6c3 100644
--- a/lib/spack/spack/test/conftest.py
+++ b/lib/spack/spack/test/conftest.py
@@ -425,7 +425,17 @@ def configuration_dir(tmpdir_factory, linux_os):
     # Create temporary 'defaults', 'site' and 'user' folders
     tmpdir.ensure('user', dir=True)
 
-    # Slightly modify compilers.yaml to look like Linux
+    # Slightly modify config.yaml and compilers.yaml
+    config_yaml = test_config.join('config.yaml')
+    modules_root = tmpdir_factory.mktemp('share')
+    tcl_root = modules_root.ensure('modules', dir=True)
+    lmod_root = modules_root.ensure('lmod', dir=True)
+    content = ''.join(config_yaml.read()).format(
+        str(tcl_root), str(lmod_root)
+    )
+    t = tmpdir.join('site', 'config.yaml')
+    t.write(content)
+
     compilers_yaml = test_config.join('compilers.yaml')
     content = ''.join(compilers_yaml.read()).format(linux_os)
     t = tmpdir.join('site', 'compilers.yaml')
diff --git a/lib/spack/spack/test/data/config/config.yaml b/lib/spack/spack/test/data/config/config.yaml
index efbe625151..4e036a3d66 100644
--- a/lib/spack/spack/test/data/config/config.yaml
+++ b/lib/spack/spack/test/data/config/config.yaml
@@ -14,4 +14,5 @@ config:
   checksum: true
   dirty: false
   module_roots:
-    tcl:    $spack/share/spack/modules
+    tcl: {0}
+    lmod: {1}
diff --git a/lib/spack/spack/test/modules/conftest.py b/lib/spack/spack/test/modules/conftest.py
index 365a5a7092..4ab129a5dd 100644
--- a/lib/spack/spack/test/modules/conftest.py
+++ b/lib/spack/spack/test/modules/conftest.py
@@ -2,16 +2,9 @@
 # Spack Project Developers. See the top-level COPYRIGHT file for details.
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
-
-import os.path
-import collections
-import contextlib
-import inspect
-
-import ruamel.yaml as yaml
 import pytest
-from six import StringIO
 
+import spack.config
 import spack.paths
 import spack.spec
 import spack.modules.common
@@ -19,34 +12,7 @@ import spack.util.path
 
 
 @pytest.fixture()
-def file_registry():
-    """Fake filesystem for modulefiles test"""
-    return collections.defaultdict(StringIO)
-
-
-@pytest.fixture()
-def filename_dict(file_registry, monkeypatch):
-    """Returns a fake open that writes on a StringIO instance instead
-    of disk.
-    """
-    @contextlib.contextmanager
-    def _mock(filename, mode):
-        if not mode == 'w':
-            raise RuntimeError('opening mode must be "w" [stringio_open]')
-
-        try:
-            yield file_registry[filename]
-        finally:
-            handle = file_registry[filename]
-            file_registry[filename] = handle.getvalue()
-            handle.close()
-    # Patch 'open' in the appropriate module
-    monkeypatch.setattr(spack.modules.common, 'open', _mock, raising=False)
-    return file_registry
-
-
-@pytest.fixture()
-def modulefile_content(filename_dict, request):
+def modulefile_content(request):
     """Returns a function that generates the content of a module file
     as a list of lines.
     """
@@ -58,13 +24,15 @@ def modulefile_content(filename_dict, request):
         spec = spack.spec.Spec(spec_str)
         spec.concretize()
         generator = writer_cls(spec)
-        generator.write()
+        generator.write(overwrite=True)
 
         # Get its filename
         filename = generator.layout.filename
 
         # Retrieve the content
-        content = filename_dict[filename].split('\n')
+        with open(filename) as f:
+            content = f.readlines()
+            content = ''.join(content).split('\n')
         generator.remove()
         return content
 
@@ -72,46 +40,6 @@ def modulefile_content(filename_dict, request):
 
 
 @pytest.fixture()
-def patch_configuration(monkeypatch, request):
-    """Reads a configuration file from the mock ones prepared for tests
-    and monkeypatches the right classes to hook it in.
-    """
-    # Class of the module file writer
-    writer_cls = getattr(request.module, 'writer_cls')
-    # Module where the module file writer is defined
-    writer_mod = inspect.getmodule(writer_cls)
-    # Key for specific settings relative to this module type
-    writer_key = str(writer_mod.__name__).split('.')[-1]
-    # Root folder for configuration
-    root_for_conf = os.path.join(
-        spack.paths.test_path, 'data', 'modules', writer_key
-    )
-
-    def _impl(filename):
-
-        file = os.path.join(root_for_conf, filename + '.yaml')
-        with open(file) as f:
-            configuration = yaml.load(f)
-
-        monkeypatch.setattr(
-            spack.modules.common,
-            'configuration',
-            configuration
-        )
-        monkeypatch.setattr(
-            writer_mod,
-            'configuration',
-            configuration[writer_key]
-        )
-        monkeypatch.setattr(
-            writer_mod,
-            'configuration_registry',
-            {}
-        )
-    return _impl
-
-
-@pytest.fixture()
 def update_template_dirs(config, monkeypatch):
     """Mocks the template directories for tests"""
     dirs = spack.config.get_config('config')['template_dirs']
diff --git a/lib/spack/spack/test/modules/tcl.py b/lib/spack/spack/test/modules/tcl.py
index ec0b47c484..ae7ef9e50e 100644
--- a/lib/spack/spack/test/modules/tcl.py
+++ b/lib/spack/spack/test/modules/tcl.py
@@ -133,8 +133,10 @@ class TestTcl(object):
         assert len([x for x in content if 'is-loaded' in x]) == 1
         assert len([x for x in content if 'module load ' in x]) == 1
 
-        # Returns a StringIO instead of a string as no module file was written
-        with pytest.raises(AttributeError):
+        # Catch "Exception" to avoid using FileNotFoundError on Python 3
+        # and IOError on Python 2 or common bases like EnvironmentError
+        # which are not officially documented
+        with pytest.raises(Exception):
             modulefile_content('callpath arch=x86-linux')
 
         content = modulefile_content('zmpi arch=x86-linux')