Imports Xunit Public Class ZipperTests Public Sub Data_is_retained() Dim tree = New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Dim sut = Zipper.FromTree(tree) Dim actual = sut.ToTree() Dim expected = New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Assert.Equal(expected, actual) End Sub Public Sub Left_right_and_value() Dim tree = New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Dim sut = Zipper.FromTree(tree) Dim actual = sut.Left().Right().Value() Dim expected = 3 Assert.Equal(expected, actual) End Sub Public Sub Dead_end() Dim tree = New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Dim sut = Zipper.FromTree(tree) Dim actual = sut.Left().Left() Assert.Null(actual) End Sub Public Sub Tree_from_deep_focus() Dim tree = New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Dim sut = Zipper.FromTree(tree) Dim actual = sut.Left().Right().ToTree() Dim expected = New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Assert.Equal(expected, actual) End Sub Public Sub Traversing_up_from_top() Dim tree = New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Dim sut = Zipper.FromTree(tree) Dim actual = sut.Up() Assert.Null(actual) End Sub Public Sub Left_right_and_up() Dim tree = New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Dim sut = Zipper.FromTree(tree) Dim actual = sut.Left().Up().Right().Up().Left().Right().Value() Dim expected = 3 Assert.Equal(expected, actual) End Sub Public Sub Test_ability_to_descend_multiple_levels_and_return() Dim tree = New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Dim sut = Zipper.FromTree(tree) Dim actual = sut.Left().Right().Up().Up().Value() Dim expected = 1 Assert.Equal(expected, actual) End Sub Public Sub Set_value() Dim tree = New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Dim sut = Zipper.FromTree(tree) Dim actual = sut.Left().SetValue(5).ToTree() Dim expected = New BinTree(1, New BinTree(5, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Assert.Equal(expected, actual) End Sub Public Sub Set_value_after_traversing_up() Dim tree = New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Dim sut = Zipper.FromTree(tree) Dim actual = sut.Left().Right().Up().SetValue(5).ToTree() Dim expected = New BinTree(1, New BinTree(5, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Assert.Equal(expected, actual) End Sub Public Sub Set_left_with_leaf() Dim tree = New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Dim sut = Zipper.FromTree(tree) Dim actual = sut.Left().SetLeft(CType(New BinTree(5, Nothing, Nothing), BinTree)).ToTree() Dim expected = New BinTree(1, New BinTree(2, New BinTree(5, Nothing, Nothing), New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Assert.Equal(expected, actual) End Sub Public Sub Set_right_with_null() Dim tree = New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Dim sut = Zipper.FromTree(tree) Dim actual = sut.Left().SetRight(Nothing).ToTree() Dim expected = New BinTree(1, New BinTree(2, Nothing, Nothing), New BinTree(4, Nothing, Nothing)) Assert.Equal(expected, actual) End Sub Public Sub Set_right_with_subtree() Dim tree = New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Dim sut = Zipper.FromTree(tree) Dim actual = sut.SetRight(CType(New BinTree(6, New BinTree(7, Nothing, Nothing), New BinTree(8, Nothing, Nothing)), BinTree)).ToTree() Dim expected = New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(6, New BinTree(7, Nothing, Nothing), New BinTree(8, Nothing, Nothing))) Assert.Equal(expected, actual) End Sub Public Sub Set_value_on_deep_focus() Dim tree = New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Dim sut = Zipper.FromTree(tree) Dim actual = sut.Left().Right().SetValue(5).ToTree() Dim expected = New BinTree(1, New BinTree(2, Nothing, New BinTree(5, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Assert.Equal(expected, actual) End Sub Public Sub Different_paths_to_same_zipper() Dim tree = New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)) Dim sut = Zipper.FromTree(tree) Dim actual = sut.Left().Up().Right() Dim expected = Zipper.FromTree(CType(New BinTree(1, New BinTree(2, Nothing, New BinTree(3, Nothing, Nothing)), New BinTree(4, Nothing, Nothing)), BinTree)).Right() Assert.Equal(expected, actual) End Sub End Class