test/mod: add checks for util.test_util

Test that `checksum.verify_file` works correctly, which internally
uses the only other utility function `checksum.hexdigest_file`.
Check all algorithms currently supported by the `org.osbuild.curl`
source.

test/mod/test_util_checksum.py

@@ -0,0 +1,34 @@
+#
+# Test for the util.checksum module
+#
+from tempfile import NamedTemporaryFile
+import pytest
+
+from osbuild.util import checksum
+
+
+# pylint: disable=line-too-long
+TEST_STRING = "I have of late, but wherefore I know not, lost all my bytes\n"
+TEST_RESULT = {
+    "md5": "537f2c2e965f5ce9c524704b58cb7660",
+    "sha1": "897b9791e74e937fccc885e093897a071c2a54fb",
+    "sha256": "16bf29978fc76774eef051739e1e9e9983bcb29285250ffddfc1955f8a3f95fb",
+    "sha384": "7f7c72cabd9af1872e22713efe02deb6234475affcc6b8c9816ce683fee2f63285b466880171f462d49fbefb0dd35ee6",
+    "sha512": "f0874cb102032ca78070c07fd4a894c3eb752b903ab758a54aa8937b2a77830bac40f1faf8ae0e206ff56c4446699a2ae4941f4a6d6556cab4a4ac072216bacc"
+}
+
+
+@pytest.fixture(name="tempfile")
+def tempfile_fixture():
+    with NamedTemporaryFile(prefix="verify-file-", mode="w") as f:
+        yield f
+
+
+@pytest.mark.parametrize("algorithm", TEST_RESULT.keys())
+def test_verify_file(algorithm, tempfile):
+    tempfile.write(TEST_STRING)
+    tempfile.flush()
+
+    digest = TEST_RESULT[algorithm]
+    full_digest = f"{algorithm}:{digest}"
+    assert checksum.verify_file(tempfile.name, full_digest), "checksums mismatch"