Polaroider : Customizing snapshot comparer

Customizing snapshot comparing

To customize the comparing of snapshots, the comparer can be altered in the SnapshotOptions.

SnapshotOptions SetComparer(Func<Line, Line, bool> comparer)

By default Line has an override of Equals. That way Lines can be compared directly with each other.

SnapshotOptions.Default.SetComparer((newline, savedline) => newline.Equals(savedline));

Examples

Ignore all whitespaces when comparing the lines with each other

var sn = new StringBuilder()
    .AppendLine("Line    1")
    .AppendLine("   Line 2")
    .AppendLine("  Line     3")
    .ToString();

var options = SnapshotOptions.Create(o =>
{
    // ignore whitespaces when comparing
    o.SetComparer((newline, savedline) => newline.Value.Replace(" ", string.Empty, StringComparison.OrdinalIgnoreCase).Equals(savedline.Value.Replace(" ", string.Empty, StringComparison.OrdinalIgnoreCase)));
});

sn.MatchSnapshot(options);