public void HasPrevious_WhenStartOffsetIsZero_ReturnsFalse()
{
// Arrange
var context = CreateContext();
// Act
var slice = SliceMetrics.Create(DbContext.Blogs, context);
// Assert
Assert.Equal(0, slice.StartIndex);
Assert.False(slice.HasPrevious);
}
public void HasPrevious_WhenStartOffsetIsGreater0_ReturnsTrue()
{
// Arrange
var context = CreateContext(
after: ConnectionUtils.OffsetToCursor(0)
);
// Act
var slice = SliceMetrics.Create(DbContext.Blogs, context);
// Assert
Assert.Equal(1, slice.StartIndex);
Assert.True(slice.HasPrevious);
}
public void HasNext_WhenDataIsSliceAndEndOffsetIsLastIndex_ReturnsFalse()
{
// Arrange
var context = CreateContext(
after: ConnectionUtils.OffsetToCursor(999)
);
// Act
var slice = SliceMetrics.Create(DbContext.Blogs, context);
// Assert
Assert.Equal(1000, slice.StartIndex);
Assert.Equal(0, slice.SliceSize);
Assert.False(slice.HasNext);
}
public void HasPrevious_WhenDataIsSliceAndStartOffsetIsZero_ReturnsFalse()
{
// Arrange
var context = CreateContext(
first: 2
);
// Act
var slice = SliceMetrics.Create(Blogs, context);
// Assert
Assert.Equal(0, slice.StartIndex);
Assert.Equal(2, slice.SliceSize);
Assert.False(slice.HasPrevious);
}
public void HasNext_WhenEndOffsetIsLessThanLastIndex_ReturnsTrue()
{
// Arrange
var context = CreateContext(
first: 10,
after: ConnectionUtils.OffsetToCursor(0)
);
// Act
var slice = SliceMetrics.Create(DbContext.Blogs, context);
// Assert
Assert.Equal(1, slice.StartIndex);
Assert.Equal(10, slice.SliceSize);
Assert.True(slice.HasNext);
}
public void HasPrevious_WhenDataIsSliceAndStartOffsetIsGreater0_ReturnsTrue()
{
// Arrange
var context = CreateContext(
first: 2,
after: ConnectionUtils.OffsetToCursor(9)
);
// Act
var slice = SliceMetrics.Create(Blogs, context);
// Assert
Assert.Equal(10, slice.StartIndex);
Assert.Equal(2, slice.SliceSize);
Assert.True(slice.HasPrevious);
}
public void Create_WhenCreateFromFullList_ReturnsListCount()
{
// Arrange
var context = CreateContext <Blog>();
// Act
var slice = SliceMetrics.Create(
DbContext.Blogs,
context
);
// Assert
Assert.Equal(fixture.TotalCount, slice.SliceSize);
Assert.Equal(fixture.TotalCount, slice.TotalCount);
Assert.Equal(0, slice.StartIndex);
Assert.False(slice.HasNext);
Assert.False(slice.HasPrevious);
}
public void Create_WhenDataSliceStartsAfterEnd_ReturnsEmptyResult()
{
// Arrange
var context = CreateContext(
first: 10,
after: ConnectionUtils.OffsetToCursor(999)
);
// Act
var slice = SliceMetrics.Create(
DbContext.Blogs,
context
);
// Assert
Assert.Equal(0, slice.SliceSize);
Assert.Equal(1000, slice.StartIndex);
Assert.False(slice.HasNext);
Assert.True(slice.HasPrevious);
}
public void Create_WhenDataDoesNotCoverRequestedRange_AdjustsStartAndEndOffsets()
{
// Arrange
var context = CreateContext(
first: 10,
after: ConnectionUtils.OffsetToCursor(995)
);
// Act
var slice = SliceMetrics.Create(
DbContext.Blogs,
context
);
// Assert
Assert.Equal(4, slice.SliceSize);
Assert.Equal(fixture.TotalCount, slice.TotalCount);
Assert.Equal(996, slice.StartIndex);
Assert.False(slice.HasNext);
Assert.True(slice.HasPrevious);
}
/// <summary>
/// From the connection context, <see cref="IResolveConnectionContext"/>,
/// it creates a <see cref="Connection{TSource}"/> based on the given <see cref="IEnumerable{TSource}"/>
/// </summary>
/// <typeparam name="TSource"></typeparam>
/// <param name="context"></param>
/// <param name="items"></param>
/// <param name="totalCount"></param>
/// <returns></returns>
public static Connection <TSource> ToConnection <TSource>(
this IResolveConnectionContext context,
IEnumerable <TSource> items,
int?totalCount = null
)
{
var metrics = SliceMetrics.Create(
items,
context,
totalCount
);
var edges = metrics.Slice
.Select((item, i) => new Edge <TSource>
{
Node = item,
Cursor = ConnectionUtils.OffsetToCursor(metrics.StartIndex + i)
})
.ToList();
var firstEdge = edges.FirstOrDefault();
var lastEdge = edges.LastOrDefault();
return(new Connection <TSource>
{
Edges = edges,
TotalCount = metrics.TotalCount,
PageInfo = new PageInfo
{
StartCursor = firstEdge?.Cursor,
EndCursor = lastEdge?.Cursor,
HasPreviousPage = metrics.HasPrevious,
HasNextPage = metrics.HasNext,
}
});
}
