Added new filters feature.

CHANGELOG.md

@@ -6,6 +6,7 @@ All notable changes to insta and cargo-insta are documented here.
 
 - Fixed an issue in `cargo-insta` where sometimes accepting inline snapshots
   would crash with an out of bounds panic.
+- Added new `filters` feature.
 
 ## 1.16.0
 

Cargo.toml

@@ -24,6 +24,9 @@ default = ["colors"]
 # snapshots.
 redactions = ["pest", "pest_derive"]
 
+# Enables support for running filters on snapshot
+filters = ["regex"]
+
 # Glob support
 glob = ["walkdir", "globset"]
 
@@ -50,6 +53,7 @@ globset = { version = "0.4.6", optional = true }
 walkdir = { version = "2.3.1", optional = true }
 similar = { version = "2.1.0", features = ["inline"] }
 once_cell = "1.9.0"
+regex = { version = "1.6.0", default-features = false, optional = true, features = ["std", "unicode"] }
 
 [dev-dependencies]
 similar-asserts = "1.2.0"

src/lib.rs

@@ -140,6 +140,7 @@
 //! * `ron`: enables RON support ([`assert_ron_snapshot!`])
 //! * `toml`: enables TOML support ([`assert_toml_snapshot!`])
 //! * `redactions`: enables support for redactions
+//! * `filters`: enables support for filters
 //! * `glob`: enables support for globbing ([`glob!`])
 //! * `colors`: enables color output (enabled by default)
 //!
@@ -161,6 +162,9 @@ mod utils;
 #[cfg(feature = "redactions")]
 mod redaction;
 
+#[cfg(feature = "filters")]
+mod filters;
+
 #[cfg(feature = "glob")]
 mod glob;
 
@@ -176,6 +180,8 @@ pub use crate::snapshot::{MetaData, Snapshot};
 /// are exposed for documentation primarily.
 pub mod internals {
     pub use crate::content::Content;
+    #[cfg(feature = "filters")]
+    pub use crate::filters::Filters;
     pub use crate::runtime::AutoName;
     pub use crate::snapshot::{MetaData, SnapshotContents};
     #[cfg(feature = "redactions")]

src/runtime.rs

@@ -472,6 +472,11 @@ pub fn assert_snapshot(
         assertion_line,
     )?;
 
+    // apply filters if they are available
+    #[cfg(feature = "filters")]
+    let new_snapshot_value =
+        Settings::with(|settings| settings.filters().apply_to(new_snapshot_value));
+
     let new_snapshot = ctx.new_snapshot(new_snapshot_value.into(), expr);
 
     // memoize the snapshot file if requested.

src/settings.rs

@@ -14,6 +14,9 @@ use crate::{
     redaction::{dynamic_redaction, sorted_redaction, ContentPath, Redaction, Selector},
 };
 
+#[cfg(feature = "filters")]
+use crate::filters::Filters;
+
 static DEFAULT_SETTINGS: Lazy<Arc<ActualSettings>> = Lazy::new(|| {
     Arc::new(ActualSettings {
         sort_maps: false,
@@ -26,6 +29,8 @@ static DEFAULT_SETTINGS: Lazy<Arc<ActualSettings>> = Lazy::new(|| {
         prepend_module_to_snapshot: true,
         #[cfg(feature = "redactions")]
         redactions: Redactions::default(),
+        #[cfg(feature = "filters")]
+        filters: Filters::default(),
         #[cfg(feature = "glob")]
         allow_empty_glob: false,
     })
@@ -62,6 +67,8 @@ pub struct ActualSettings {
     pub prepend_module_to_snapshot: bool,
     #[cfg(feature = "redactions")]
     pub redactions: Redactions,
+    #[cfg(feature = "filters")]
+    pub filters: Filters,
     #[cfg(feature = "glob")]
     pub allow_empty_glob: bool,
 }
@@ -104,6 +111,11 @@ impl ActualSettings {
         self.redactions = r.into();
     }
 
+    #[cfg(feature = "filters")]
+    pub fn filters<F: Into<Filters>>(&mut self, f: F) {
+        self.filters = f.into();
+    }
+
     #[cfg(feature = "glob")]
     pub fn allow_empty_glob(&mut self, value: bool) {
         self.allow_empty_glob = value;
@@ -370,7 +382,7 @@ impl Settings {
     /// The default set is empty.
     #[cfg(feature = "redactions")]
     pub fn set_redactions<R: Into<Redactions>>(&mut self, redactions: R) {
-        self._private_inner_mut().redactions = redactions.into();
+        self._private_inner_mut().redactions(redactions);
     }
 
     /// Removes all redactions.
@@ -389,6 +401,50 @@ impl Settings {
             .map(|&(ref a, ref b)| (a, &**b))
     }
 
+    /// Adds a new filter.
+    ///
+    /// Filters are similar to redactions but are applied as regex onto the final snapshot
+    /// value.  This can be used to perform modifications to the snapshot string that would
+    /// be impossible to do with redactions because for instance the value is just a string.
+    ///
+    /// The first argument is the [`regex`] pattern to apply, the second is a replacement
+    /// string.  The replacement string has the same functionality as the second argument
+    /// to [`Regex::replace`](regex::Regex::replace).
+    ///
+    /// This is useful to perform some cleanup procedures on the snapshot for unstable values.
+    ///
+    /// ```rust
+    /// # use insta::Settings;
+    /// # async fn foo() {
+    /// # let mut settings = Settings::new();
+    /// settings.add_filter(r"\b[[:xdigit:]]{32}\b", "[UID]");
+    /// # }
+    /// ```
+    #[cfg(feature = "filters")]
+    pub fn add_filter<S: Into<String>>(&mut self, regex: &str, replacement: S) {
+        self._private_inner_mut().filters.add(regex, replacement);
+    }
+
+    /// Replaces the currently set filters.
+    ///
+    /// The default set is empty.
+    #[cfg(feature = "filters")]
+    pub fn set_filters<F: Into<Filters>>(&mut self, filters: F) {
+        self._private_inner_mut().filters(filters);
+    }
+
+    /// Removes all filters.
+    #[cfg(feature = "filters")]
+    pub fn clear_filters(&mut self) {
+        self._private_inner_mut().filters.clear();
+    }
+
+    /// Returns the current filters
+    #[cfg(feature = "filters")]
+    pub(crate) fn filters(&self) -> &Filters {
+        &self.inner.filters
+    }
+
     /// Sets the snapshot path.
     ///
     /// If not absolute it's relative to where the test is in.

src/snapshot.rs

@@ -1,3 +1,4 @@
+use std::borrow::Cow;
 use std::error::Error;
 use std::fs;
 use std::io::{BufRead, BufReader, Write};
@@ -349,6 +350,15 @@ impl SnapshotContents {
     }
 }
 
+impl<'a> From<Cow<'a, str>> for SnapshotContents {
+    fn from(value: Cow<'a, str>) -> Self {
+        match value {
+            Cow::Borrowed(s) => SnapshotContents::from(s),
+            Cow::Owned(s) => SnapshotContents::from(s),
+        }
+    }
+}
+
 impl From<&str> for SnapshotContents {
     fn from(value: &str) -> SnapshotContents {
         // make sure we have unix newlines consistently