Zhanyong Wan 0bdccf4aa2 Add a DistanceFrom() matcher for general distance comparison.
We have a bunch of matchers for asserting that a value is near the target value, e.g.
`DoubleNear()` and `FloatNear()`. These matchers only work for specific types (`double` and `float`). They are not flexible enough to support other types that have the notion of a "distance" (e.g. N-dimensional points and vectors, which are commonly used in ML).

In this diff, we generalize the idea to a `DistanceFrom(target, get_distance, m)` matcher that works on arbitrary types that have the "distance" concept (the `get_distance` argument is optional and can be omitted for types that support `-`, and `std::abs()`). What it does:

1. compute the distance between the value and the target using `get_distance(value, target)`; if `get_distance` is omitted, compute the distance as `std::abs(value - target)`.
2. match the distance against matcher `m`; if the match succeeds, the `DistanceFrom()` match succeeds.

Examples:

```
  // 0.5's distance from 0.6 should be <= 0.2.
  EXPECT_THAT(0.5, DistanceFrom(0.6, Le(0.2)));

  Vector2D v1(3.0, 4.0), v2(3.2, 6.0);
  // v1's distance from v2, as computed by EuclideanDistance(v1, v2),
  // should be >= 1.0.
  EXPECT_THAT(v1, DistanceFrom(v2, EuclideanDistance, Ge(1.0)));
```

PiperOrigin-RevId: 734593292
Change-Id: Id6bb7074dc4aa4d8abd78b57ad2426637e590de5
2025-03-07 09:54:00 -08:00
..
actions.md Add SaveArgByMove 2025-02-10 10:22:27 -08:00
assertions.md This change adjusts how ASSERT_NEAR and EXPECT_NEAR treats infinity, such that ASSERT_NEAR(inf, inf, 0) passes. This makes the behavior more consistent with ASSERT_EQ(inf, inf) which succeeds. 2024-10-14 10:13:58 -07:00
matchers.md Add a DistanceFrom() matcher for general distance comparison. 2025-03-07 09:54:00 -08:00
mocking.md Revert incorrect update. 2024-02-22 08:48:24 -08:00
testing.md Add a testing::ConvertGenerator overload that accepts a converting functor. This allows the use of classes that do not have a converting ctor to the desired type. 2025-03-04 10:40:25 -08:00