Imports System Imports Xunit Public Class CircularBufferTests Public Sub Reading_empty_buffer_should_fail() Dim buffer = New CircularBuffer(Of Integer)(capacity:=1) Assert.Throws(Of InvalidOperationException)(Function() buffer.Read()) End Sub Public Sub Can_read_an_item_just_written() Dim buffer = New CircularBuffer(Of Integer)(capacity:=1) buffer.Write(1) Assert.Equal(1, buffer.Read()) End Sub Public Sub Each_item_may_only_be_read_once() Dim buffer = New CircularBuffer(Of Integer)(capacity:=1) buffer.Write(1) Assert.Equal(1, buffer.Read()) Assert.Throws(Of InvalidOperationException)(Function() buffer.Read()) End Sub Public Sub Items_are_read_in_the_order_they_are_written() Dim buffer = New CircularBuffer(Of Integer)(capacity:=2) buffer.Write(1) buffer.Write(2) Assert.Equal(1, buffer.Read()) Assert.Equal(2, buffer.Read()) End Sub Public Sub Full_buffer_cant_be_written_to() Dim buffer = New CircularBuffer(Of Integer)(capacity:=1) buffer.Write(1) Assert.Throws(Of InvalidOperationException)(Sub() buffer.Write(2)) End Sub Public Sub A_read_frees_up_capacity_for_another_write() Dim buffer = New CircularBuffer(Of Integer)(capacity:=1) buffer.Write(1) Assert.Equal(1, buffer.Read()) buffer.Write(2) Assert.Equal(2, buffer.Read()) End Sub Public Sub Read_position_is_maintained_even_across_multiple_writes() Dim buffer = New CircularBuffer(Of Integer)(capacity:=3) buffer.Write(1) buffer.Write(2) Assert.Equal(1, buffer.Read()) buffer.Write(3) Assert.Equal(2, buffer.Read()) Assert.Equal(3, buffer.Read()) End Sub Public Sub Items_cleared_out_of_buffer_cant_be_read() Dim buffer = New CircularBuffer(Of Integer)(capacity:=3) buffer.Write(1) buffer.Write(2) buffer.Clear() Assert.Throws(Of InvalidOperationException)(Function() buffer.Read()) End Sub Public Sub Clear_frees_up_capacity_for_another_write() Dim buffer = New CircularBuffer(Of Integer)(capacity:=1) buffer.Write(1) buffer.Clear() buffer.Write(2) Assert.Equal(2, buffer.Read()) End Sub Public Sub Clear_does_nothing_on_empty_buffer() Dim buffer = New CircularBuffer(Of Integer)(capacity:=1) buffer.Clear() buffer.Write(1) Assert.Equal(1, buffer.Read()) End Sub Public Sub Overwrite_acts_like_write_on_non_full_buffer() Dim buffer = New CircularBuffer(Of Integer)(capacity:=2) buffer.Write(1) buffer.Overwrite(2) Assert.Equal(1, buffer.Read()) Assert.Equal(2, buffer.Read()) End Sub Public Sub Overwrite_replaces_the_oldest_item_on_full_buffer() Dim buffer = New CircularBuffer(Of Integer)(capacity:=2) buffer.Write(1) buffer.Write(2) buffer.Overwrite(3) Assert.Equal(2, buffer.Read()) Assert.Equal(3, buffer.Read()) End Sub Public Sub Overwrite_replaces_the_oldest_item_remaining_in_buffer_following_a_read() Dim buffer = New CircularBuffer(Of Integer)(capacity:=3) buffer.Write(1) buffer.Write(2) buffer.Write(3) Assert.Equal(1, buffer.Read()) buffer.Write(4) buffer.Overwrite(5) Assert.Equal(3, buffer.Read()) Assert.Equal(4, buffer.Read()) Assert.Equal(5, buffer.Read()) End Sub Public Sub Initial_clear_does_not_affect_wrapping_around() Dim buffer = New CircularBuffer(Of Integer)(capacity:=2) buffer.Clear() buffer.Write(1) buffer.Write(2) buffer.Overwrite(3) buffer.Overwrite(4) Assert.Equal(3, buffer.Read()) Assert.Equal(4, buffer.Read()) Assert.Throws(Of InvalidOperationException)(Function() buffer.Read()) End Sub End Class