const std = @import("std");
const CircularAllocator= @import("zcirc.zig").CircularAllocator;

test "something" {
    // Much like working with an ArenaAllocator
    var circle = CircularAllocator.init(std.testing.allocator);
    defer circle.deinit();
    var allocator = circle.allocator();

    // Allocations work like any other allocator
    var a = try allocator.create(u32);
    a.* = 12;
    var b = try allocator.alloc(u8, a.*);

    // The total "busy" bytes in our internal buffers include the
    // space for a and b, plus some slop for alignment and bookkeeping
    const overhead = @alignOf(CircularAllocator.Meta) + @sizeOf(CircularAllocator.Meta) - 2;
    try std.testing.expectEqual(
        (b.len + @sizeOf(u32)) + (@alignOf(u8) + @alignOf(u32)) + 2*overhead,
        circle.count()
    );

    // Deletes all data up through (including) the pointer `a`
    circle.free_left(a);

    // The total "busy" bytes only track space used for `b` now
    try std.testing.expectEqual(b.len + @alignOf(u8) + overhead, circle.count());

    // Deletes all data from (including) the slice `b`
    circle.free_right(b);

    // Our internal buffers are completely empty. New allocations will
    // attempt to reuse that space.
    try std.testing.expectEqual(@as(usize, 0), circle.count());
}