Cover the case contract_name is not found

Author: Yoichi Hirai

raiden_contracts/contract_source_manager.py

@@ -197,3 +197,10 @@ def _verify_single_precompiled_checksum(
             f"checksum of {contract_name} does not match. got {precompiled_checksum} != "
             "expected {expected_checksum}"
         )
+
+
+def verify_single_precompiled_checksum_on_nonexistent_contract_name() -> None:
+    """ A functiohn for testing the case where the contract name is not found """
+    _verify_single_precompiled_checksum(
+        checked_checksums={}, contract_name="a", expected_checksum="abc"
+    )

raiden_contracts/tests/test_contracts_compilation.py

@@ -22,6 +22,7 @@
     ContractSourceManager,
     ContractSourceManagerVerificationError,
     contracts_source_path,
+    verify_single_precompiled_checksum_on_nonexistent_contract_name,
 )
 
 
@@ -256,3 +257,8 @@ def test_contract_source_manager_constructor_with_wrong_type() -> None:
     """ ConstructSourceManager's constructor raises TypeError on a wrong kind of argument """
     with pytest.raises(TypeError):
         ContractSourceManager(None)  # type: ignore
+
+
+def test_verify_single_precompiled_cyhecksum_on_nonexistent_contract_name() -> None:
+    with pytest.raises(ContractSourceManagerVerificationError, match="No checksum for"):
+        verify_single_precompiled_checksum_on_nonexistent_contract_name()