- ✅ Error messages include file type context

---

### 2. FilenameExtractorEnhancedTest.java
**Purpose**: Test FilenameExtractor edge cases and new documentation.

**Key Test Areas**:
- Parameter handling (null, empty, missing)
- Special character handling
- Input stream validation (not consumption)
- Edge cases (long filenames, paths, whitespace)

**Test Count**: 10 tests

**Key Scenarios**:
- ✅ Valid filename extraction

      // Number of edges remaining is unknown (node's incident edges have been removed).
      AbstractNetworkTest.validateNetwork(network);

      for (int i = numNodesToRemove; i < NUM_NODES; ++i) {
        assertThat(network.removeNode(nodeList.get(i))).isTrue();
      }

      assertThat(network.nodes()).isEmpty();
      assertThat(network.edges()).isEmpty(); // no edges can remain if there's no nodes

        SmbException ex = assertThrows(SmbException.class, () -> transport.hasCapability(42));
        assertTrue(ex.getMessage().contains("failed"));
        verify(transport).hasCapability(42);
    }

    // Edge: disconnected status toggles
    @ParameterizedTest
    @DisplayName("isDisconnected reflects current mocked state")
    @ValueSource(booleans = { true, false })
    void isDisconnected_states(boolean disconnected) {

        while (resultWithDoubleSelfLoop.hasNext()) {
          EndpointPair<N> edge = resultWithDoubleSelfLoop.next();
          if (edge.nodeU().equals(edge.nodeV())) {
            if (!alreadySeenSelfLoop.getAndSet(true)) {
              return edge;
            }
          } else {
            return edge;
          }
        }
        return endOfData();
      }
    };
  }

    int edgeStart = graphString.indexOf("edges:");
    String nodeString = graphString.substring(nodeStart, edgeStart);

    Network<N, EndpointPair<N>> asNetwork = graph.asNetwork();
    // Don't call AbstractNetworkTest.validateNetwork(asNetwork).  Mutual recursion.
    assertThat(graph.nodes()).isEqualTo(asNetwork.nodes());
    assertThat(graph.edges()).hasSize(asNetwork.edges().size());

import org.junit.jupiter.params.provider.MethodSource;
import org.mockito.Mockito;
import org.mockito.junit.jupiter.MockitoExtension;

/**
 * Tests for SmbBasicFileInfo interface.
 * The tests exercise typical, edge, and null scenarios using a simple
 * implementation and a Mockito mock to verify interactions.
 */
@ExtendWith(MockitoExtension.class)
public class SmbBasicFileInfoTest {

    /**

      mutableValueGraph.addNode(node);
      return this;
    }

    /**
     * Adds an edge connecting {@code nodeU} to {@code nodeV} if one is not already present, and
     * sets a value for that edge to {@code value} (overwriting the existing value, if any).
     *
     * <p>If the graph is directed, the resultant edge will be directed; otherwise, it will be
     * undirected.
     *

import org.jspecify.annotations.Nullable;

/**
 * A class to represent the set of edges connecting an (implicit) origin node to a target node.
 *
 * <p>The {@link #outEdgeToNode} map allows this class to work on networks with parallel edges. See
 * {@link EdgesConnecting} for a class that is more efficient but forbids parallel edges.
 *
 * @author James Sexton
 * @param <E> Edge parameter type
 */

    void mock_noInteractions() {
        // Arrange/Act: do nothing
        // Assert: verify no interactions
        verifyNoInteractions(mockEntry);
    }

    // --- Fake implementation tests (happy path and edge cases) ---

    @Test
    @DisplayName("Fake implementation returns provided values (happy path)")
    void fakeImplementation_happyPath() {
        // Arrange

    ImmutableMultimap.Builder<Character, Character> graphMapBuilder = ImmutableMultimap.builder();
    for (String edge : edges) {
      checkArgument(
          edge.length() == 2, "Expecting each edge to consist of 2 characters but got %s", edge);
      char node1 = edge.charAt(0);
      char node2 = edge.charAt(1);
      graphMapBuilder.put(node1, node2);