build system: add the initial set of pytest-based build system tests

tools/test_build_system/test_build_system_helpers/snapshot.py

@@ -0,0 +1,61 @@
+# SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+# SPDX-License-Identifier: Apache-2.0
+import fnmatch
+import glob
+import os
+from typing import List, Optional, Tuple, Union
+
+
+class Snapshot:
+    """
+    Helper class for working with build snapshots.
+    A snapshot is a set of files along with their modification timestamps.
+    """
+    def __init__(self, files: List[str]) -> None:
+        """Create a snapshot of the given list of files, recording their mtimes"""
+        self.info: List[Tuple[str, int]] = []
+        for file in sorted(files):
+            st = os.stat(file)
+            self.info.append((file, st.st_mtime_ns))
+
+    def assert_same(self, other: 'Snapshot') -> None:
+        """Assert that this snapshot has the same files and mtimes as the other snapshot"""
+        for my_info, other_info in zip(self.info, other.info):
+            assert my_info[0] == other_info[0], f'Snapshots mismatch, expected file {my_info[0]}, found {other_info[0]}'
+            assert my_info[1] == other_info[1], f'File {my_info[0]} timestamp has changed! diff={(other_info[1]-my_info[1])/10**9}'
+
+    def assert_different(self, other: 'Snapshot') -> None:
+        """Assert that this snapshot has the same files as the other snapshot, but all mtimes are different"""
+        for my_info, other_info in zip(self.info, other.info):
+            assert my_info[0] == other_info[0], f'Snapshots mismatch, expected file {my_info[0]}, found {other_info[0]}'
+            assert my_info[1] != other_info[1], f'File {my_info[0]} timestamp has not changed! ({my_info[1]})'
+
+
+def get_snapshot(glob_patterns: Union[str, List[str]],
+                 exclude_patterns: Optional[Union[str, List[str]]] = None) -> Snapshot:
+    """Return a snapshot including the files matched by glob_patterns, and excluding those matched by exclude_patterns"""
+    if isinstance(glob_patterns, str):
+        glob_patterns = [glob_patterns]
+
+    if isinstance(exclude_patterns, str):
+        exclude_patterns_list = [exclude_patterns]
+    elif exclude_patterns is None:
+        exclude_patterns_list = []
+    elif isinstance(exclude_patterns, list):
+        exclude_patterns_list = exclude_patterns
+    else:
+        raise ValueError(f'Unexpcted type of exclude_patterns: ({type(exclude_patterns)}')
+
+    # whether the path found by glob.glob should be excluded?
+    def should_exclude(filename: str) -> bool:
+        return os.path.isdir(filename) or \
+            any((fnmatch.fnmatch(filename, pattern) for pattern in exclude_patterns_list))
+
+    files_to_snapshot: List[str] = []
+    for pattern in glob_patterns:
+        found = filter(lambda f: not should_exclude(f),
+                       glob.glob(pattern, recursive=True))
+        if not found:
+            raise RuntimeError(f'failed to match any files with pattern {pattern}')
+        files_to_snapshot.extend(found)
+    return Snapshot(files_to_snapshot)