(feat) hasTableCell(): Match the string value of cell item.

[johnzeringue]

In some cases, it is useful to match a string value against a table
cell's value, regardless of type. For example, when testing a table
of doubles, the string comparison might allow for small discrepancies
in the digital representation that are imperceptible to the user.
This is consistent with BDD principles: implementation details aren't
relevant in testing.

In testfx-legacy, this functionality is provided in the
containsCell method. Without adding a suitable replacement in
testfx-core, it will be more difficult for some developers to
migrate to TestFX 4.

[hastebrot]

Thanks for the PR. Never mind the failing tests as long as the test run with framebuffer passes.

We could add a table with integers to TableViewMatchersTest. And maybe table cells with null value to catch edge-cases.

[hastebrot]

We could improve the cohesion and readability with the introduction of hasItemValue() in TableViewMatchers:

private static boolean hasCellValue(Cell cell,
                                    Object value) {
    return !cell.isEmpty() && hasItemValue(cell.getItem(), value);
}

private static boolean hasItemValue(Object item,
                                    Object value) {
    return Objects.equals(item, value) || Objects.equals(item.toString(), value);
}

Here is a modified TableViewMatchersTests with tests for the toString() calls.

public class TableViewMatchersTest extends FxRobot {

    //---------------------------------------------------------------------------------------------
    // FIELDS.
    //---------------------------------------------------------------------------------------------

    @Rule
    public ExpectedException exception = ExpectedException.none();

    public TableView<Map> tableView;

    //---------------------------------------------------------------------------------------------
    // FIXTURE METHODS.
    //---------------------------------------------------------------------------------------------

    @BeforeClass
    public static void setupSpec() throws Exception {
        FxToolkit.registerPrimaryStage();
    }

    @Before
    public void setup() throws Exception {
        FxToolkit.setupSceneRoot(() -> {
            tableView = new TableView<>();
            tableView.setItems(observableArrayList(
                ImmutableMap.of("name", "alice", "age", 30),
                ImmutableMap.of("name", "bob", "age", 31),
                ImmutableMap.of("name", "carol"),
                ImmutableMap.of("name", "dave")
            ));
            TableColumn<Map, String> tableColumn0 = new TableColumn<>("name");
            tableColumn0.setCellValueFactory(new MapValueFactory<>("name"));
            TableColumn<Map, Integer> tableColumn1 = new TableColumn<>("age");
            tableColumn1.setCellValueFactory(new MapValueFactory<>("age"));
            tableView.getColumns().setAll(tableColumn0, tableColumn1);
            return new StackPane(tableView);
        });
        FxToolkit.showStage();
    }

    //---------------------------------------------------------------------------------------------
    // FEATURE METHODS.
    //---------------------------------------------------------------------------------------------

    @Test
    public void hasTableCell() {
        // expect:
        assertThat(tableView, TableViewMatchers.hasTableCell("alice"));
        assertThat(tableView, TableViewMatchers.hasTableCell("bob"));
    }

    @Test
    public void hasTableCell_fails() {
        // expect:
        exception.expect(AssertionError.class);
        exception.expectMessage("Expected: TableView has table cell \"foobar\"\n");

        assertThat(tableView, TableViewMatchers.hasTableCell("foobar"));
    }

    @Test
    public void hasTableCell_with_toString() {
        // expect:
        assertThat(tableView, TableViewMatchers.hasTableCell("30"));

        // and:
        assertThat(tableView, TableViewMatchers.hasTableCell(31));
    }

    @Test
    public void hasTableCell_with_null_fails() {
        // expect:
        exception.expect(AssertionError.class);
        exception.expectMessage("Expected: TableView has table cell \"null\"\n");

        assertThat(tableView, TableViewMatchers.hasTableCell(null));
    }

    @Test
    public void hasItems() {
        // expect:
        assertThat(tableView, TableViewMatchers.hasItems(4));
    }

    @Test
    public void hasItems_fails() {
        // expect:
        exception.expect(AssertionError.class);
        exception.expectMessage("Expected: TableView has 0 items\n");

        assertThat(tableView, TableViewMatchers.hasItems(0));
    }

}

[johnzeringue]

I've added in your tests and made your readability fixes.

I've also made another pull request to address the Travis issue (at least as I understand it). If your happy with that one, we can merge it first and I can rebase the changes into this one (so the Travis build passes) before we merge.

[hastebrot]

Your rebased commit passed the tests, so I merged this. Very good work.