fn diag_locations_ok() -> Bool {
    let source: Span<u8> = "alpha\nbeta\r\ngamma"
    if std.diag.line(source, 0) != 1 {
        return false
    }
    if std.diag.line(source, 6) != 2 {
        return false
    }
    if std.diag.column(source, 7) != 2 {
        return false
    }
    if std.diag.lineStart(source, 7) != 6 {
        return false
    }
    if std.diag.lineEnd(source, 7) != 10 {
        return false
    }
    if !std.mem.eql(std.diag.lineText(source, 7), "beta") {
        return false
    }
    if std.diag.line(source, 100) != 3 {
        return false
    }
    if std.diag.column(source, 100) != 6 {
        return false
    }
    return true
}

fn diag_ranges_ok() -> Bool {
    let source: Span<u8> = "0123456789"
    if std.diag.rangeLen(source, 2, 5) != 3 {
        return false
    }
    if std.diag.rangeLen(source, 8, 4) != 0 {
        return false
    }
    if std.diag.rangeLen(source, 8, 40) != 2 {
        return false
    }
    if !std.mem.eql(std.diag.rangeText(source, 2, 5), "234") {
        return false
    }
    if !std.mem.eql(std.diag.rangeText(source, 8, 4), "") {
        return false
    }
    return std.mem.eql(std.diag.rangeText(source, 8, 40), "89")
}

fn diag_format_ok() -> Bool {
    let source: Span<u8> = "alpha\nbeta\r\ngamma"
    var storage: [32]u8 = [0_u8; 32]
    let formatted: Maybe<Span<u8>> = std.diag.formatOffsetLocation(storage, "input.0", source, 7)
    var direct_storage: [32]u8 = [0_u8; 32]
    let direct: Maybe<Span<u8>> = std.diag.formatLocation(direct_storage, "input.0", 2, 2)
    var small_storage: [4]u8 = [0_u8; 4]
    let small: Maybe<Span<u8>> = std.diag.formatLocation(small_storage, "input.0", 2, 2)
    if !formatted.has || !direct.has {
        return false
    }
    if small.has {
        return false
    }
    return std.mem.eql(formatted.value, "input.0:2:2") && std.mem.eql(direct.value, "input.0:2:2")
}

pub fn main(world: World) -> Void raises {
    if diag_locations_ok() && diag_ranges_ok() && diag_format_ok() {
        check world.out.write("std diag ok\n")
    } else {
        check world.out.write("std diag failed\n")
    }
}