Implement tests for string transformation functions

test_min_cost_string_conversion.py

@@ -0,0 +1,27 @@
+import pytest
+from strings.min_cost_string_conversion import (
+    compute_transform_tables,
+    assemble_transformation,
+)
+
+
+def test_empty_strings():
+    costs, ops = compute_transform_tables("", "", 1, 1, 1, 1)
+    assert costs == [[0]]
+    assert assemble_transformation(ops, 0, 0) == []
+
+
+def test_copy_only():
+    costs, ops = compute_transform_tables("abc", "abc", 1, 2, 3, 3)
+    assert costs[-1][-1] == 3  # cost = sum of copy costs
+    assert assemble_transformation(ops, len(ops) - 1, len(ops[0]) - 1) == [
+        "Ca",
+        "Cb",
+        "Cc",
+    ]
+
+
+def test_insert_only():
+    costs, ops = compute_transform_tables("", "xyz", 1, 1, 1, 1)
+    seq = assemble_transformation(ops, 0, len(ops[0]) - 1)
+    assert seq == ["Ix", "Iy", "Iz"]