Expand similarity tests

tests/utils/test_similarity.py

@@ -1,15 +1,54 @@
-import pytest
-
 from docugami_dfm_benchmarks.utils.similarity import compute_f1
 
 
-@pytest.mark.parametrize(
-    "text1,text2,expected_f1",
-    [
-        ("This is a test", "This is a test", 1.0),  # Exact match
-        ("One two a three", "one two   three", 1.0),  # Exact match modulo article, whitespace and casing
-        ("One two a three", "   four five a six", 0.0),  # No match
-    ],
-)
-def test_compute_f1(text1: str, text2: str, expected_f1: float) -> None:
+def test_compute_f1_exact_match() -> None:
+    """
+    Test compute_f1 with texts that are exactly the same.
+    Expected F1 score should be 1.0, indicating a perfect match.
+    """
+    text1 = "This is a test"
+    text2 = "This is a test"
+    expected_f1 = 1.0
+    assert compute_f1(text1, text2) == expected_f1
+
+
+def test_compute_f1_normalized_match() -> None:
+    """
+    Test compute_f1 with texts that match exactly when normalized.
+    This includes removal of articles, ignoring whitespace differences, and case insensitivity.
+    Expected F1 score should be 1.0, indicating a perfect match after normalization.
+    """
+    text1 = "One two a three"
+    text2 = "one two   three"
+    expected_f1 = 1.0
+    assert compute_f1(text1, text2) == expected_f1
+
+
+def test_compute_f1_no_match() -> None:
+    """
+    Test compute_f1 with texts that have no matching tokens.
+    Expected F1 score should be 0.0, indicating no similarity between the texts.
+    """
+    text1 = "One two a three"
+    text2 = "   four five a six"
+    expected_f1 = 0.0
+    assert compute_f1(text1, text2) == expected_f1
+
+
+def test_compute_f1_partial_match() -> None:
+    """
+    Test compute_f1 with partially overlapping tokens to ensure correct partial matching.
+    """
+    text1 = "quick brown fox"
+    text2 = "lazy brown dog"
+    # Expected F1 considering overlap is "brown", with precision = recall = F1 = 1/3
+    expected_f1 = 2 * (1 / 3 * 1 / 3) / (1 / 3 + 1 / 3)
     assert compute_f1(text1, text2) == expected_f1
+
+
+def test_compute_f1_with_empty_strings() -> None:
+    """
+    Test compute_f1 with one or both strings empty to check edge case handling.
+    """
+    assert compute_f1("", "") == 1.0  # Both empty, perfect match
+    assert compute_f1("quick brown fox", "") == 0.0  # One empty, no match