Struct Settings

pub struct Settings { /* private fields */ }

Configures how insta operates at test time.

Settings are always bound to a thread and some default settings are always available. These settings can be changed and influence how insta behaves on that thread. They can either temporarily or permanently changed.

This can be used to influence how the snapshot macros operate. For instance it can be useful to force ordering of maps when unordered structures are used through settings.

Some of the settings can be changed but shouldn’t as it will make it harder for tools like cargo-insta or an editor integration to locate the snapshot files.

Settings can also be configured with the with_settings! macro.

Example:

use insta;

let mut settings = insta::Settings::clone_current();
settings.set_sort_maps(true);
settings.bind(|| {
    // runs the assertion with the changed settings enabled
    insta::assert_snapshot!(...);
});

Implementations

impl Settings

pub fn new() -> Settings

Returns the default settings.

It’s recommended to use clone_current instead so that already applied modifications are not discarded.

pub fn clone_current() -> Settings

Returns a copy of the current settings.

pub fn set_sort_maps(&mut self, value: bool)

Enables forceful sorting of maps before serialization.

Note that this only applies to snapshots that undergo serialization (eg: does not work for assert_debug_snapshot!.)

The default value is false.

pub fn sort_maps(&self) -> bool

Returns the current value for map sorting.

pub fn set_prepend_module_to_snapshot(&mut self, value: bool)

Disables prepending of modules to the snapshot filename.

By default the filename of a snapshot is <module>__<name>.snap. Setting this flag to false changes the snapshot filename to just <name>.snap.

The default value is true.

pub fn prepend_module_to_snapshot(&self) -> bool

Returns the current value for module name prepending.

pub fn set_snapshot_suffix<I: Into<String>>(&mut self, suffix: I)

Sets the snapshot suffix.

The snapshot suffix is added to all snapshot names with an @ sign between. For instance if the snapshot suffix is set to "foo" and the snapshot would be named "snapshot" it turns into "snapshot@foo". This is useful to separate snapshots if you want to use test parameterization.

pub fn remove_snapshot_suffix(&mut self)

Removes the snapshot suffix.

pub fn snapshot_suffix(&self) -> Option<&str>

Returns the current snapshot suffix.

pub fn set_input_file<P: AsRef<Path>>(&mut self, p: P)

Sets the input file reference.

This value is completely unused by the snapshot testing system but it lets you store some meta data with a snapshot that refers you back to the input file. The path stored here is made relative to the workspace root before storing with the snapshot.

pub fn remove_input_file(&mut self)

Removes the input file reference.

pub fn input_file(&self) -> Option<&Path>

Returns the current input file reference.

pub fn set_description<S: Into<String>>(&mut self, value: S)

Sets the description.

The description is stored alongside the snapshot and will be displayed in the diff UI. When a snapshot is captured the Rust expression for that snapshot is always retained. However sometimes that information is not super useful by itself, particularly when working with loops and generated tests. In that case the description can be set as extra information.

See also set_info.

pub fn remove_description(&mut self)

Removes the description.

pub fn description(&self) -> Option<&str>

Returns the current description

pub fn set_info<S: Serialize>(&mut self, s: &S)

Sets the info.

The info is similar to description but for structured data. This is stored with the snapshot and shown in the review UI. This for instance can be used to show extended information that can make a reviewer better understand what the snapshot is supposed to be testing.

As an example the input parameters to the function that creates the snapshot can be persisted here.

Alternatively you can use set_raw_info instead.

pub fn set_raw_info(&mut self, content: &Content)

Sets the info from a content object.

This works like set_info but does not require serde.

pub fn remove_info(&mut self)

Removes the info.

pub fn has_info(&self) -> bool

Returns the current info

pub fn set_omit_expression(&mut self, value: bool)

If set to true, does not retain the expression in the snapshot.

pub fn omit_expression(&self) -> bool

Returns true if expressions are omitted from snapshots.

pub fn set_snapshot_path<P: AsRef<Path>>(&mut self, path: P)

Sets the snapshot path.

If not absolute it’s relative to where the test is in.

Defaults to snapshots.

pub fn snapshot_path(&self) -> &Path

Returns the snapshot path.

pub fn bind<F: FnOnce() -> R, R>(&self, f: F) -> R

Runs a function with the current settings bound to the thread.

This is an alternative to bind_to_scope which does not require holding on to a drop guard. The return value of the closure is passed through.

let mut settings = Settings::clone_current();
settings.set_sort_maps(true);
settings.bind(|| {
    // do stuff here
});

pub fn bind_async<F: Future<Output = T>, T>( &self, future: F, ) -> impl Future<Output = T>

Like bind but for futures.

This lets you bind settings for the duration of a future like this:

let settings = Settings::new();
settings.bind_async(async {
    // do assertions here
}).await;

pub fn bind_to_scope(&self) -> SettingsBindDropGuard

Binds the settings to the current thread and resets when the drop guard is released.

This is the recommended way to temporarily bind settings and replaces the earlier bind_to_scope and relies on drop guards. An alterantive is bind which binds for the duration of the block it wraps.

let mut settings = Settings::clone_current();
settings.set_sort_maps(true);
let _guard = settings.bind_to_scope();
// do stuff here

Trait Implementations

impl Clone for Settings

fn clone(&self) -> Settings

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Default for Settings

fn default() -> Settings

Returns the “default value” for a type.