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// Copyright 2022 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
use crate::matcher::{Matcher, MatcherResult};
use std::{fmt::Debug, marker::PhantomData};
/// Matches a `Result` containing `Err` with a value matched by `inner`.
///
/// ```
/// # use googletest::prelude::*;
/// # fn should_pass() -> googletest::Result<()> {
/// verify_that!(Err::<(), _>("Some error"), err(eq("Some error")))?; // Passes
/// # Ok(())
/// # }
/// # fn should_fail_1() -> googletest::Result<()> {
/// verify_that!(Ok::<_, &str>("A value"), err(eq("A value")))?; // Fails
/// # Ok(())
/// # }
/// # fn should_fail_2() -> googletest::Result<()> {
/// verify_that!(Err::<(), _>("Some error"), err(eq("Some other error")))?; // Fails
/// # Ok(())
/// # }
/// # should_pass().unwrap();
/// # should_fail_1().unwrap_err();
/// # should_fail_2().unwrap_err();
/// ```
pub fn err<T: Debug, E: Debug>(
inner: impl Matcher<ActualT = E>,
) -> impl Matcher<ActualT = std::result::Result<T, E>> {
ErrMatcher::<T, E, _> { inner, phantom_t: Default::default(), phantom_e: Default::default() }
}
struct ErrMatcher<T, E, InnerMatcherT> {
inner: InnerMatcherT,
phantom_t: PhantomData<T>,
phantom_e: PhantomData<E>,
}
impl<T: Debug, E: Debug, InnerMatcherT: Matcher<ActualT = E>> Matcher
for ErrMatcher<T, E, InnerMatcherT>
{
type ActualT = std::result::Result<T, E>;
fn matches(&self, actual: &Self::ActualT) -> MatcherResult {
actual.as_ref().err().map(|v| self.inner.matches(v)).unwrap_or(MatcherResult::NoMatch)
}
fn explain_match(&self, actual: &Self::ActualT) -> String {
match actual {
Err(e) => format!("which is an error {}", self.inner.explain_match(e)),
Ok(_) => "which is a success".to_string(),
}
}
fn describe(&self, matcher_result: MatcherResult) -> String {
match matcher_result {
MatcherResult::Match => {
format!("is an error which {}", self.inner.describe(MatcherResult::Match))
}
MatcherResult::NoMatch => {
format!(
"is a success or is an error containing a value which {}",
self.inner.describe(MatcherResult::NoMatch)
)
}
}
}
}
#[cfg(test)]
mod tests {
use super::err;
use crate::matcher::{Matcher, MatcherResult};
use crate::prelude::*;
use indoc::indoc;
#[test]
fn err_matches_result_with_err_value() -> Result<()> {
let matcher = err(eq(1));
let value: std::result::Result<i32, i32> = Err(1);
let result = matcher.matches(&value);
verify_that!(result, eq(MatcherResult::Match))
}
#[test]
fn err_does_not_match_result_with_wrong_err_value() -> Result<()> {
let matcher = err(eq(1));
let value: std::result::Result<i32, i32> = Err(0);
let result = matcher.matches(&value);
verify_that!(result, eq(MatcherResult::NoMatch))
}
#[test]
fn err_does_not_match_result_with_ok() -> Result<()> {
let matcher = err(eq(1));
let value: std::result::Result<i32, i32> = Ok(1);
let result = matcher.matches(&value);
verify_that!(result, eq(MatcherResult::NoMatch))
}
#[test]
fn err_full_error_message() -> Result<()> {
let result = verify_that!(Err::<i32, i32>(1), err(eq(2)));
verify_that!(
result,
err(displays_as(contains_substring(indoc!(
"
Value of: Err::<i32, i32>(1)
Expected: is an error which is equal to 2
Actual: Err(1),
which is an error which isn't equal to 2
"
))))
)
}
#[test]
fn err_describe_matches() -> Result<()> {
let matcher = super::ErrMatcher::<i32, i32, _> {
inner: eq(1),
phantom_t: Default::default(),
phantom_e: Default::default(),
};
verify_that!(matcher.describe(MatcherResult::Match), eq("is an error which is equal to 1"))
}
}
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