facet-assert: Structural Assertions

Two values with identical content pass assert_same! — no PartialEq required.

#[derive(Facet)]
struct Config {
    host: String,
    port: u16,
    debug: bool,
    tags: Vec<String>,
}

Config {
  host: "localhost",
  port: 8080,
  debug: true,
  tags: Vec<String> [
    "prod",
    "api",
  ],
}

Different type names (Config vs ConfigV2) with the same structure are considered "same". Useful for comparing DTOs across API versions or testing serialization roundtrips.

#[derive(Facet)]
struct Config {
    host: String,
    port: u16,
    debug: bool,
    tags: Vec<String>,
}

Config {
  host: "localhost",
  port: 8080,
  debug: true,
  tags: Vec<String> [
    "prod",
  ],
}

Nested structs are compared recursively, field by field.

#[derive(Facet)]
struct Person {
    name: String,
    age: u32,
    address: Address,
}

#[derive(Facet)]
struct Address {
    street: String,
    city: String,
}

Person {
  name: "Alice",
  age: 30,
  address: Address {
    street: "123 Main St",
    city: "Springfield",
  },
}

When values differ, you get a precise structural diff showing exactly which fields changed and at what path — not just a wall of red/green text.

.host:
  - "localhost"
  + "prod.example.com"
.port:
  - 8080
  + 443
.debug:
  - true
  + false
.tags[1] (only in left):
  - "api"

Vector comparisons show exactly which indices differ, which elements were added, and which were removed.

[2]:
  - 3
  + 99
[4] (only in left):
  - 5