zig/test/behavior/this.zig

const expect = @import("std").testing.expect;

const module = @This();

fn Point(comptime T: type) type {
    return struct {
        const Self = @This();
        x: T,
        y: T,

        fn addOne(self: *Self) void {
            self.x += 1;
            self.y += 1;
        }
    };
}

fn add(x: i32, y: i32) i32 {
    return x + y;
}

test "this refer to module call private fn" {
    try expect(module.add(1, 2) == 3);
}

test "this refer to container" {
    var pt: Point(i32) = undefined;
    pt.x = 12;
    pt.y = 34;
    Point(i32).addOne(&pt);
    try expect(pt.x == 13);
    try expect(pt.y == 35);
}