[TESTS] Add tests for the s3 module

pyproject.toml

@@ -25,6 +25,7 @@ pygments = "^2.19.1"
 [tool.poetry.group.dev.dependencies]
 bandit = "^1.8.3"
 black = "^25.1.0"
+moto = "^5.1.9"
 
 [tool.poetry.group.docs.dependencies]
 sphinx-rtd-theme = "^3.0.2"

src/gardenlinux/features/cname.py

@@ -136,7 +136,7 @@ def platform(self) -> str:
         :return: (str) Flavor
         """
 
-        return re.split("[_-]", self._flavor, 1)[0]
+        return re.split("[_-]", self._flavor, maxsplit=1)[0]
 
     @property
     def version(self) -> Optional[str]:

tests/s3/conftest.py

@@ -0,0 +1,63 @@
+# -*- coding: utf-8 -*-
+
+from dataclasses import dataclass
+from moto import mock_aws
+from hashlib import md5, sha256
+import boto3
+import pytest
+
+from gardenlinux.features.cname import CName as RealCName
+
+BUCKET_NAME = "test-bucket"
+REGION = "us-east-1"
+
+
+@dataclass(frozen=True)
+class S3Env:
+    s3: object
+    bucket_name: str
+    tmp_path: str
+    cname: str
+
+
+def make_cname(
+    flavor: str = "testcname",
+    arch: str = "amd64",
+    version: str = "1234.1",
+    commit: str = "abc123",
+) -> str:
+    """
+    Helper function to build cname. Can be used to customized the cname.
+    """
+    return f"{flavor}-{arch}-{version}-{commit}"
+
+
+# Helpers to compute digests for fake files
+def dummy_digest(data: bytes, algo: str) -> str:
+    """
+    Dummy for file_digest() to compute hashes for in-memory byte streams
+    """
+    content = data.read()
+    data.seek(0)  # Reset byte cursor to start for multiple uses
+
+    if algo == "md5":
+        return md5(content)  # nosec B324
+    elif algo == "sha256":
+        return sha256(content)
+    else:
+        raise ValueError(f"Unsupported algo: {algo}")
+
+
+@pytest.fixture(autouse=True)
+def s3_setup(tmp_path, monkeypatch):
+    """
+    Provides a clean S3 setup for each test.
+    """
+    with mock_aws():
+        s3 = boto3.resource("s3", region_name=REGION)
+        s3.create_bucket(Bucket=BUCKET_NAME)
+
+        monkeypatch.setattr("gardenlinux.s3.s3_artifacts.file_digest", dummy_digest)
+
+        cname = make_cname()
+        yield S3Env(s3, BUCKET_NAME, tmp_path, cname)