You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: 203_error_positions.rs
    path of file: ./repos/ron/tests
    
    the code of the file until where you have to start completion: use std::num::NonZeroU32;

use ron::error::{Error, Position, SpannedError};
use serde::{
    de::{Deserialize, Error as DeError, Unexpected},
    Deserializer,
};

#[derive(Debug, serde::Deserialize, PartialEq)]
#[serde(deny_unknown_fields)]
enum Test {
    TupleVariant(i32, String),
    StructVariant { a: bool, b: NonZeroU32, c: i32 },
}

#[derive(Debug, PartialEq)] // GRCOV_EXCL_LINE
struct TypeError;

impl<'de> Deserialize<'de> for TypeError {
    fn deserialize<D: Deserializer<'de>>(_deserializer: D) -> Result<Self, D::Error> {
        Err(D::Error::invalid_type(Unexpected::Unit, &"impossible"))
    }
}

#[test]
fn test_error_positions() {
    assert_eq!(
        ron::from_str::<TypeError>("  
    
fn test_error_positions() {
    assert_eq!(
        ron::from_str::<TypeError>("  ()"),
        Err(SpannedError {
            code: Error::InvalidValueForType {
                expected: String::from("impossible"),
                found: String::from("a unit value"),
            },
            position: Position { line: 1, col: 3 },
        })
    );

    assert_eq!(
        ron::from_str::<Test>("StructVariant(a: true, b: 0, c: -42)"),
        Err(SpannedError {
            code: Error::InvalidValueForType {
                expected: String::from("a nonzero u32"),
                found: String::from("the unsigned integer `0`"),
            },
            position: Position { line: 1, col: 28 },
        })
    );

    assert_eq!(
        ron::from_str::<Test>("TupleVariant(42)"),
        Err(SpannedError {
            code: Error::ExpectedDifferentLength {
                expected: String::from("tuple variant Test::TupleVariant with 2 elements"),
                found: 1,
            },
            position: Position { line: 1, col: 16 },
        })
    );

    assert_eq!(
        ron::from_str::<Test>("NotAVariant"),
        Err(SpannedError {
            code: Error::NoSuchEnumVariant {
                expected: &["TupleVariant", "StructVariant"],
                found: String::from("NotAVariant"),
                outer: Some(String::from("Test")),
            },
            position: Position { line: 1, col: 12 },
        })
    );

    assert_eq!(
        ron::from_str::<Test>("StructVariant(a: true, b: 1, c: -42, d: \"gotcha\")"),
        Err(SpannedError {
            code: Error::NoSuchStructField {
                expected: &["a", "b", "c"],
                found: String::from("d"),
                outer: Some(String::from("StructVariant")),
            },
            position: Position { line: 1, col: 39 },
        })
    );

    assert_eq!(
        ron::from_str::<Test>("StructVariant(a: true, c: -42)"),
        Err(SpannedError {
            code: Error::MissingStructField {
                field: "b",
                outer: Some(String::from("StructVariant")),
            },
            position: Position { line: 1, col: 30 },
        })
    );

    assert_eq!(
        ron::from_str::<Test>("StructVariant(a: true, b: 1, a: false, c: -42)"),
        Err(SpannedError {
            code: Error::DuplicateStructField {
                field: "a",
                outer: Some(String::from("StructVariant")),
            },
            position: Position { line: 1, col: 31 },
        })
    );
}