tests/storage/virtual_directory_import.py: New file

tests/storage/virtual_directory_import.py

+import os
+import pytest
+from tests.testutils import cli
+
+from buildstream.storage import CasBasedDirectory
+
+
+class FakeContext():
+    def __init__(self):
+        self.config_cache_quota = "65536"
+
+    def get_projects(self):
+        return []
+
+# This is a set of example file system contents. The test attempts to import
+# each on top of each other to test importing works consistently.
+# Each tuple is defined as (<filename>, <type>, <content>). Type can be
+# 'F' (file), 'S' (symlink) or 'D' (directory) with content being the contents
+# for a file or the destination for a symlink.
+root_filesets = [
+    [('a/b/c/textfile1', 'F', 'This is textfile 1\n')],
+    [('a/b/c/textfile1', 'F', 'This is the replacement textfile 1\n')],
+    [('a/b/d', 'D', '')],
+    [('a/b/c', 'S', '/a/b/d')],
+    [('a/b/d', 'D', ''), ('a/b/c', 'S', '/a/b/d')],
+]
+
+empty_hash_ref = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+
+
+def generate_import_roots(directory):
+    for fileset in range(1, len(root_filesets) + 1):
+        rootname = "root{}".format(fileset)
+        rootdir = os.path.join(directory, "content", rootname)
+
+        for (path, typesymbol, content) in root_filesets[fileset - 1]:
+            if typesymbol == 'F':
+                (dirnames, filename) = os.path.split(path)
+                os.makedirs(os.path.join(rootdir, dirnames), exist_ok=True)
+                with open(os.path.join(rootdir, dirnames, filename), "wt") as f:
+                    f.write(content)
+            elif typesymbol == 'D':
+                os.makedirs(os.path.join(rootdir, path), exist_ok=True)
+            elif typesymbol == 'S':
+                (dirnames, filename) = os.path.split(path)
+                os.makedirs(os.path.join(rootdir, dirnames), exist_ok=True)
+                os.symlink(content, os.path.join(rootdir, path))
+
+
+def file_contents(path):
+    with open(path, "r") as f:
+        result = f.read()
+    return result
+
+
+def file_contents_are(path, contents):
+    return file_contents(path) == contents
+
+
+def create_new_vdir(root_number, fake_context, tmpdir):
+    d = CasBasedDirectory(fake_context)
+    d.import_files(os.path.join(tmpdir, "content", "root{}".format(root_number)))
+    assert d.ref.hash != empty_hash_ref
+    return d
+
+
+def combinations(integer_range):
+    for x in integer_range:
+        for y in integer_range:
+            yield (x, y)
+
+
+def resolve_symlinks(path, root):
+    """ A function to resolve symlinks inside 'path' components apart from the last one.
+        For example, resolve_symlinks('/a/b/c/d', '/a/b')
+        will return '/a/b/f/d' if /a/b/c is a symlink to /a/b/f. The final component of
+        'path' is not resolved, because we typically want to inspect the symlink found
+        at that path, not its target.
+
+    """
+    components = path.split(os.path.sep)
+    location = root
+    for i in range(0, len(components) - 1):
+        location = os.path.join(location, components[i])
+        if os.path.islink(location):
+            # Resolve the link, add on all the remaining components
+            target = os.path.join(os.readlink(location))
+            tail = os.path.sep.join(components[i + 1:])
+
+            if target.startswith(os.path.sep):
+                # Absolute link - relative to root
+                location = os.path.join(root, target, tail)
+            else:
+                # Relative link - relative to symlink location
+                location = os.path.join(location, target)
+            return resolve_symlinks(location, root)
+    # If we got here, no symlinks were found. Add on the final component and return.
+    location = os.path.join(location, components[-1])
+    return location
+
+
+def directory_not_empty(path):
+    return os.listdir(path)
+
+
+@pytest.mark.parametrize("original,overlay", combinations([1, 2, 3, 4, 5]))
+def test_cas_import(cli, tmpdir, original, overlay):
+    fake_context = FakeContext()
+    fake_context.artifactdir = tmpdir
+    # Create some fake content
+    generate_import_roots(tmpdir)
+
+    d = create_new_vdir(original, fake_context, tmpdir)
+    d2 = create_new_vdir(overlay, fake_context, tmpdir)
+    d.import_files(d2)
+    d.export_files(os.path.join(tmpdir, "output"))
+
+    for item in root_filesets[overlay - 1]:
+        (path, typename, content) = item
+        realpath = resolve_symlinks(path, os.path.join(tmpdir, "output"))
+        if typename == 'F':
+            if os.path.isdir(realpath) and directory_not_empty(realpath):
+                # The file should not have overwritten the directory in this case.
+                pass
+            else:
+                assert os.path.isfile(realpath), "{} did not exist in the combined virtual directory".format(path)
+                assert file_contents_are(realpath, content)
+        elif typename == 'S':
+            if os.path.isdir(realpath) and directory_not_empty(realpath):
+                # The symlink should not have overwritten the directory in this case.
+                pass
+            else:
+                assert os.path.islink(realpath)
+                assert os.readlink(realpath) == content
+        elif typename == 'D':
+            # Note that isdir accepts symlinks to dirs, so a symlink to a dir is acceptable.
+            assert os.path.isdir(realpath)