[](https://travis-ci.org/davidpdrsn/assert-json-diff)
# assert-json-diff
This crate includes macros for comparing two JSON values. It is designed to give much
more helpful error messages than the standard [`assert_eq!`]. It basically does a diff of the
two objects and tells you the exact differences. This is useful when asserting that two large
JSON objects are the same.
It uses the [`serde_json::Value`] type to represent JSON.
[`serde_json::Value`]: https://docs.serde.rs/serde_json/value/enum.Value.html
[`assert_eq!`]: https://doc.rust-lang.org/std/macro.assert_eq.html
### Install
```toml
[dependencies]
assert-json-diff = "0.2.0"
```
### Partial matching
If you want to assert that one JSON value is "included" in another use
[`assert_json_include`](macro.assert_json_include.html):
```rust
#[macro_use]
extern crate assert_json_diff;
#[macro_use]
extern crate serde_json;
fn main() {
let a = json!({
"data": {
"users": [
{
"id": 1,
"country": {
"name": "Denmark"
}
},
{
"id": 24,
"country": {
"name": "Denmark"
}
}
]
}
});
let b = json!({
"data": {
"users": [
{
"id": 1,
"country": {
"name": "Sweden"
}
},
{
"id": 2,
"country": {
"name": "Denmark"
}
}
]
}
});
assert_json_include!(actual: a, expected: b)
}
```
This will panic with the error message:
```
json atoms at path ".data.users[0].country.name" are not equal:
expected:
"Sweden"
actual:
"Denmark"
json atoms at path ".data.users[1].id" are not equal:
expected:
2
actual:
24
```
[`assert_json_include`](macro.assert_json_include.html) allows extra data in `actual` but not in `expected`. That is so you can verify just a part
of the JSON without having to specify the whole thing. For example this test passes:
```rust
#[macro_use]
extern crate assert_json_diff;
#[macro_use]
extern crate serde_json;
fn main() {
assert_json_include!(
actual: json!({
"a": { "b": 1 },
}),
expected: json!({
"a": {},
})
)
}
```
However `expected` cannot contain additional data so this test fails:
```rust
#[macro_use]
extern crate assert_json_diff;
#[macro_use]
extern crate serde_json;
fn main() {
assert_json_include!(
actual: json!({
"a": {},
}),
expected: json!({
"a": { "b": 1 },
})
)
}
```
That will print
```
json atom at path ".a.b" is missing from expected
```
### Exact matching
If you want to ensure two JSON values are *exactly* the same, use [`assert_json_eq`](macro.assert_json_eq.html).
```rust
#[macro_use]
extern crate assert_json_diff;
#[macro_use]
extern crate serde_json;
fn main() {
assert_json_eq!(
json!({ "a": { "b": 1 } }),
json!({ "a": {} })
)
}
```
This will panic with the error message:
```
json atom at path ".a.b" is missing from rhs
```
License: MIT