Allow --sigkey-file to be a symlink

Also adds the first tests (using pytest) & a short paragraph to the
README on how to run them.

1 files changed, 66 insertions, 0 deletions

diff --git a/sigsum-witness_test.py b/sigsum-witness_test.py
new file mode 100644
index 0000000..3c0241b
--- /dev/null
+++ b/sigsum-witness_test.py
@@ -0,0 +1,66 @@
+import importlib
+
+import pytest
+
+witness = importlib.import_module("sigsum-witness")  # To import a module with a '-'
+
+
+class Test_check_sigkeyfile:
+    def test_file_ok(self, tmp_path):
+        path = tmp_path / "key"
+        path.touch(mode=0o700)
+        witness.check_sigkeyfile(path)
+
+    def test_file_notfound(self, tmp_path):
+        path = tmp_path / "key"
+        with pytest.raises(
+            witness.SigKeyFileError,
+            match=f"ERROR: File not found: {path}",
+        ):
+            witness.check_sigkeyfile(path)
+
+    def test_notafile(self, tmp_path):
+        path = tmp_path / "key"
+        path.mkdir()
+        with pytest.raises(
+            witness.SigKeyFileError,
+            match=f"ERROR: Signing key file {path} must be a regular file",
+        ):
+            witness.check_sigkeyfile(path)
+
+    def test_file_badmode(self, tmp_path):
+        path = tmp_path / "key"
+        path.touch(mode=0o755)
+        with pytest.raises(
+            witness.SigKeyFileError,
+            match=f"ERROR: Signing key file {path} permissions too lax: 0755",
+        ):
+            witness.check_sigkeyfile(path)
+
+    def test_symlink_ok(self, tmp_path):
+        filepath = tmp_path / "thekey"
+        filepath.touch(mode=0o700)
+        linkpath = tmp_path / "key"
+        linkpath.symlink_to(filepath)
+        assert witness.check_sigkeyfile(linkpath) is None
+
+    def test_symlink_badmode(self, tmp_path):
+        filepath = tmp_path / "thekey"
+        filepath.touch(mode=0o755)
+        linkpath = tmp_path / "key"
+        linkpath.symlink_to(filepath)
+        with pytest.raises(
+            witness.SigKeyFileError,
+            match=f"ERROR: Signing key file {linkpath} permissions too lax: 0755",
+        ):
+            witness.check_sigkeyfile(linkpath)
+
+    def test_symlink_dangling(self, tmp_path):
+        filepath = tmp_path / "thekey"
+        linkpath = tmp_path / "key"
+        linkpath.symlink_to(filepath)
+        with pytest.raises(
+            witness.SigKeyFileError,
+            match=f"ERROR: File not found: {linkpath}",
+        ):
+            witness.check_sigkeyfile(linkpath)