feat(assert): Allow comparing json to jsonlines

Fixes #348

crates/snapbox/src/assert/mod.rs

@@ -118,8 +118,8 @@ impl Assert {
         }
 
         // On `expected` being an error, make a best guess
-        let format = expected.intended_format();
-        actual = actual.coerce_to(format);
+        actual = actual.coerce_to(expected.against_format());
+        actual = actual.coerce_to(expected.intended_format());
 
         if self.normalize_paths && expected.filters.is_paths_set() {
             actual = FilterPaths.filter(actual);

crates/snapbox/src/data/filters.rs

@@ -1,6 +1,9 @@
+use crate::data::DataFormat;
+
 #[derive(Copy, Clone, Default, Debug, PartialEq, Eq)]
 pub(crate) struct FilterSet {
     flags: usize,
+    against: Option<DataFormat>,
 }
 
 impl FilterSet {
@@ -9,7 +12,10 @@ impl FilterSet {
     }
 
     pub(crate) const fn empty() -> Self {
-        Self { flags: 0 }
+        Self {
+            flags: 0,
+            against: None,
+        }
     }
 
     pub(crate) fn redactions(mut self) -> Self {
@@ -32,6 +38,11 @@ impl FilterSet {
         self
     }
 
+    pub(crate) fn against(mut self, format: DataFormat) -> Self {
+        self.against = Some(format);
+        self
+    }
+
     pub(crate) const fn is_redaction_set(&self) -> bool {
         self.is_set(Self::REDACTIONS)
     }
@@ -47,6 +58,10 @@ impl FilterSet {
     pub(crate) const fn is_unordered_set(&self) -> bool {
         self.is_set(Self::UNORDERED)
     }
+
+    pub(crate) const fn get_against(&self) -> Option<DataFormat> {
+        self.against
+    }
 }
 
 impl FilterSet {

crates/snapbox/src/data/mod.rs

@@ -192,6 +192,67 @@ pub trait IntoData: Sized {
         self.is_termsvg()
     }
 
+    /// Override the type this snapshot will be compared against
+    ///
+    /// Normally, the `actual` data is coerced to [`IntoData::is`].
+    /// This allows overriding that so you can store your snapshot in a more readable, diffable
+    /// format.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// # #[cfg(feature = "json")] {
+    /// use snapbox::prelude::*;
+    /// use snapbox::str;
+    ///
+    /// let expected = str![[r#"{"hello": "world"}"#]]
+    ///     .against(snapbox::data::DataFormat::JsonLines);
+    /// # }
+    /// ```
+    fn against(self, format: DataFormat) -> Data {
+        self.into_data().against(format)
+    }
+
+    /// Initialize as json or [`Error`][DataFormat::Error]
+    ///
+    /// This is generally used for `expected` data
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// # #[cfg(feature = "json")] {
+    /// use snapbox::prelude::*;
+    /// use snapbox::str;
+    ///
+    /// let expected = str![[r#"{"hello": "world"}"#]]
+    ///     .is_json();
+    /// # }
+    /// ```
+    #[cfg(feature = "json")]
+    fn against_json(self) -> Data {
+        self.against(DataFormat::Json)
+    }
+
+    /// Initialize as json lines or [`Error`][DataFormat::Error]
+    ///
+    /// This is generally used for `expected` data
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// # #[cfg(feature = "json")] {
+    /// use snapbox::prelude::*;
+    /// use snapbox::str;
+    ///
+    /// let expected = str![[r#"{"hello": "world"}"#]]
+    ///     .against_jsonlines();
+    /// # }
+    /// ```
+    #[cfg(feature = "json")]
+    fn against_jsonlines(self) -> Data {
+        self.against(DataFormat::JsonLines)
+    }
+
     /// Convert to [`Data`], applying defaults
     fn into_data(self) -> Data;
 }
@@ -577,6 +638,29 @@ impl Data {
         })
     }
 
+    /// Override the type this snapshot will be compared against
+    ///
+    /// Normally, the `actual` data is coerced to [`Data::is`].
+    /// This allows overriding that so you can store your snapshot in a more readable, diffable
+    /// format.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// # #[cfg(feature = "json")] {
+    /// use snapbox::prelude::*;
+    /// use snapbox::str;
+    ///
+    /// let expected = str![[r#"{"hello": "world"}"#]]
+    ///     .is(snapbox::data::DataFormat::Json)
+    ///     .against(snapbox::data::DataFormat::JsonLines);
+    /// # }
+    /// ```
+    fn against(mut self, format: DataFormat) -> Data {
+        self.filters = self.filters.against(format);
+        self
+    }
+
     /// Convert `Self` to [`format`][DataFormat] if possible
     ///
     /// This is generally used on `actual` data to make it match `expected`
@@ -592,6 +676,10 @@ impl Data {
             (DataInner::Json(inner), DataFormat::Json) => DataInner::Json(inner),
             #[cfg(feature = "json")]
             (DataInner::JsonLines(inner), DataFormat::JsonLines) => DataInner::JsonLines(inner),
+            #[cfg(feature = "json")]
+            (DataInner::JsonLines(inner), DataFormat::Json) => DataInner::Json(inner),
+            #[cfg(feature = "json")]
+            (DataInner::Json(inner), DataFormat::JsonLines) => DataInner::JsonLines(inner),
             #[cfg(feature = "term-svg")]
             (DataInner::TermSvg(inner), DataFormat::TermSvg) => DataInner::TermSvg(inner),
             (DataInner::Binary(inner), _) => {
@@ -705,6 +793,12 @@ impl Data {
         }
     }
 
+    pub(crate) fn against_format(&self) -> DataFormat {
+        self.filters
+            .get_against()
+            .unwrap_or_else(|| self.intended_format())
+    }
+
     pub(crate) fn relevant(&self) -> Option<&str> {
         match &self.inner {
             DataInner::Error(_) => None,

crates/snapbox/tests/testsuite/assert.rs

@@ -38,11 +38,18 @@ fn actual_expected_formats_differ() {
 {"order": 3}
 "#,
         str![[r#"
-{}
-{"order":1}
-{"order":2}
-{"order":3}
-
-"#]].is_jsonlines(),
+[
+  {},
+  {
+    "order": 1
+  },
+  {
+    "order": 2
+  },
+  {
+    "order": 3
+  }
+]
+"#]].is_json().against_jsonlines(),
     );
 }