Extract post-processing functions from config

We can split the process of interpreting configuration files into 2 steps:

1. The parsing the file contents from strings to value objects
   that can be understand by Python (for example a string with a comma
   separated list of keywords into an actual Python list of strings).

2. The expansion (or post-processing) of these values according to the
   semantics ``setuptools`` assign to them (for example a configuration field
   with the ``file:`` directive should be expanded from a list of file paths to
   a single string with the contents of those files concatenated)

The idea of this change is to extract the functions responsible for (2.)
into a new module, so they can be reused between different config file
formats.

1 files changed, 83 insertions, 0 deletions

diff --git a/setuptools/tests/config/test_expand.py b/setuptools/tests/config/test_expand.py
new file mode 100644
index 00000000..03ee6841
--- /dev/null
+++ b/setuptools/tests/config/test_expand.py
@@ -0,0 +1,83 @@
+import pytest
+
+from distutils.errors import DistutilsOptionError
+from setuptools.config import expand
+from setuptools.sandbox import pushd
+
+
+def write_files(files, root_dir):
+    for file, content in files.items():
+        path = root_dir / file
+        path.parent.mkdir(exist_ok=True, parents=True)
+        path.write_text(content)
+
+
+def test_glob_relative(tmp_path):
+    files = {
+        os.path.join("dir1", "dir2", "dir3", "file1.txt"),
+        os.path.join("dir1", "dir2", "file2.txt"),
+        os.path.join("dir1", "file3.txt"),
+        os.path.join("a.ini"),
+        os.path.join("b.ini"),
+        os.path.join("dir1", "c.ini"),
+        os.path.join("dir1", "dir2", "a.ini"),
+    }
+
+    write_files({k: "" for k in files}, tmp_path)
+    patterns = ["**/*.txt", "[ab].*", "**/[ac].ini"]
+    with pushd(tmp_path):
+        assert set(expand.glob_relative(patterns)) == files
+
+
+def test_read_files(tmp_path):
+    files = {
+        "a.txt": "a",
+        "dir1/b.txt": "b",
+        "dir1/dir2/c.txt": "c"
+    }
+    write_files(files, tmp_path)
+    with pushd(tmp_path):
+        assert expand.read_files(list(files)) == "a\nb\nc"
+
+    with pushd(tmp_path / "dir1"), pytest.raises(DistutilsOptionError):
+        expand.read_files(["../a.txt"])
+
+
+def test_read_attr(tmp_path):
+    files = {
+        "pkg/__init__.py": "",
+        "pkg/sub/__init__.py": "VERSION = '0.1.1'",
+        "pkg/sub/mod.py": (
+            "VALUES = {'a': 0, 'b': {42}, 'c': (0, 1, 1)}\n"
+            "raise SystemExit(1)"
+        ),
+    }
+    write_files(files, tmp_path)
+    # Make sure it can read the attr statically without evaluating the module
+    with pushd(tmp_path):
+        assert expand.read_attr('pkg.sub.VERSION') == '0.1.1'
+        values = expand.read_attr('lib.mod.VALUES', {'lib': 'pkg/sub'})
+    assert values['a'] == 0
+    assert values['b'] == {42}
+    assert values['c'] == (0, 1, 1)
+
+
+def test_resolve_class():
+    from setuptools.command.sdist import sdist
+    assert expand.resolve_class("setuptools.command.sdist.sdist") == sdist
+
+
+def test_find_packages(tmp_path):
+    files = {
+        "pkg/__init__.py",
+        "other/__init__.py",
+        "dir1/dir2/__init__.py",
+    }
+
+    write_files({k: "" for k in files}, tmp_path)
+    with pushd(tmp_path):
+        assert set(expand.find_packages(where=['.'])) == {"pkg", "other"}
+        expected = {"pkg", "other", "dir2"}
+        assert set(expand.find_packages(where=['.', "dir1"])) == expected
+        expected = {"pkg", "other", "dir1", "dir1.dir2"}
+        assert set(expand.find_packages(namespaces="True")) == expected