Add unittests for verification.py (#10)

This adds previously missing unittests for the `verification.py`
module.

Author: s-heppner

test/test_verification.py

@@ -0,0 +1,84 @@
+import unittest
+from typing import List, Set
+
+from bibtex_linter.verification import check_required_fields, check_omitted_fields, verify, linter_rule
+from bibtex_linter.parser import BibTeXEntry
+
+
+@linter_rule(entry_type="test_entry_type")
+def example_linter_rule(entry: BibTeXEntry) -> List[str]:
+    violations = []
+    required_fields: Set[str] = {"author", "title", "howpublished", "year"}
+    omitted_fields: Set[str] = {"language", "organization", "address", "pages", "url"}
+    violations.extend(check_required_fields(entry, required_fields))
+    violations.extend(check_omitted_fields(entry, omitted_fields))
+    return violations
+
+
+class TestVerification(unittest.TestCase):
+    def test_check_required_fields_missing(self) -> None:
+        entry = BibTeXEntry(
+            entry_type="test_entry_type",
+            name="missing_fields",
+            fields={"author": "Jane"}
+        )
+        expected = ["Entry 'missing_fields' misses the following required fields: [howpublished, title, year]"]
+        actual = check_required_fields(entry, {"author", "title", "howpublished", "year"})
+        self.assertEqual(expected, actual)
+
+    def test_check_required_fields_complete(self) -> None:
+        entry = BibTeXEntry(
+            entry_type="test_entry_type",
+            name="complete",
+            fields={"author": "Jane", "title": "Work", "howpublished": "Online", "year": "2020"}
+        )
+        self.assertEqual([], check_required_fields(entry, {"author", "title", "howpublished", "year"}))
+
+    def test_check_omitted_fields_present(self) -> None:
+        entry = BibTeXEntry(
+            entry_type="test_entry_type",
+            name="omit_test",
+            fields={"author": "Jane", "language": "en", "url": "example.com"}
+        )
+        expected = [
+            "Entry 'omit_test' has fields present that would be omitted in the compiled document: "
+            "[language, url]. This could lead to a loss of information."
+        ]
+        actual = check_omitted_fields(entry, {"language", "organization", "address", "pages", "url"})
+        self.assertEqual(expected, actual)
+
+    def test_check_omitted_fields_absent(self) -> None:
+        entry = BibTeXEntry(
+            entry_type="test_entry_type",
+            name="omit_ok",
+            fields={"author": "Jane", "title": "Work"}
+        )
+        self.assertEqual([], check_omitted_fields(entry, {"url"}))
+
+    def test_verify_combined_rule(self) -> None:
+        entry = BibTeXEntry(
+            entry_type="test_entry_type",
+            name="bad_entry",
+            fields={"author": "Jane", "url": "http://example.org"}
+        )
+        expected = [
+            "Entry 'bad_entry' misses the following required fields: [howpublished, title, year]",
+            "Entry 'bad_entry' has fields present that would be omitted in the compiled document: [url]. "
+            "This could lead to a loss of information."
+        ]
+        actual = verify(entry)
+        self.assertEqual(expected, actual)
+
+    def test_verify_skips_different_entry_type(self) -> None:
+        entry = BibTeXEntry(
+            entry_type="unrelated_type",  # does not match the rule's "test_entry_type"
+            name="skipped_entry",
+            fields={"author": "Someone", "url": "http://example.org"}
+        )
+        actual = verify(entry)
+        expected: List[str] = []  # No rules should apply
+        self.assertEqual(expected, actual)
+
+
+if __name__ == "__main__":
+    unittest.main()