feat: Support format (#45)

Adds support for the `format` validation keyword. Additions of, and
changes to, `format`s are considered breaking. Removals are not
breaking.

Author: brhutchins

src/diff_walker.rs

@@ -356,6 +356,37 @@ impl<F: FnMut(Change)> DiffWalker<F> {
         Ok(())
     }
 
+    fn diff_format(&mut self, json_path: &str, lhs: &mut SchemaObject, rhs: &mut SchemaObject) {
+        match (&lhs.format, &rhs.format) {
+            (Some(lhs_fmt), Some(rhs_fmt)) if lhs_fmt != rhs_fmt => {
+                (self.cb)(Change {
+                    path: json_path.to_owned(),
+                    change: ChangeKind::FormatChange {
+                        old_format: lhs_fmt.clone(),
+                        new_format: rhs_fmt.clone(),
+                    },
+                });
+            }
+            (Some(removed_fmt), None) => {
+                (self.cb)(Change {
+                    path: json_path.to_owned(),
+                    change: ChangeKind::FormatRemove {
+                        removed: removed_fmt.clone(),
+                    },
+                });
+            }
+            (None, Some(added_fmt)) => {
+                (self.cb)(Change {
+                    path: json_path.to_owned(),
+                    change: ChangeKind::FormatAdd {
+                        added: added_fmt.clone(),
+                    },
+                });
+            }
+            _ => {} // No change or both None
+        }
+    }
+
     fn resolve_references(
         &self,
         lhs: &mut SchemaObject,
@@ -464,6 +495,7 @@ impl<F: FnMut(Change)> DiffWalker<F> {
             self.diff_instance_types(json_path, lhs, rhs);
         }
         self.diff_const(json_path, lhs, rhs);
+        self.diff_format(json_path, lhs, rhs);
         // If we split the types, we don't want to compare type-specific properties
         // because they are already compared in the `Self::diff_any_of`
         if !is_lhs_split && !is_rhs_split {

src/types.rs

@@ -107,6 +107,23 @@ pub enum ChangeKind {
         /// The property that is now required
         property: String,
     },
+    /// A format constraint has been added.
+    FormatAdd {
+        /// The format that was added.
+        added: String,
+    },
+    /// A format constraint has been removed.
+    FormatRemove {
+        /// The format that was removed.
+        removed: String,
+    },
+    /// A format constraint has been changed.
+    FormatChange {
+        /// The old format value.
+        old_format: String,
+        /// The new format value.
+        new_format: String,
+    },
 }
 
 impl ChangeKind {
@@ -150,6 +167,9 @@ impl ChangeKind {
             Self::TupleChange { .. } => true,
             Self::RequiredRemove { .. } => false,
             Self::RequiredAdd { .. } => true,
+            Self::FormatAdd { .. } => true,
+            Self::FormatRemove { .. } => false,
+            Self::FormatChange { .. } => true,
         }
     }
 }

tests/fixtures/format/format_add.json

@@ -0,0 +1,4 @@
+{
+  "lhs": { "type": "string" },
+  "rhs": { "type": "string", "format": "email" }
+}

tests/fixtures/format/format_change.json

@@ -0,0 +1,4 @@
+{
+  "lhs": { "type": "string", "format": "uuid" },
+  "rhs": { "type": "string", "format": "date-time" }
+}

tests/fixtures/format/format_remove.json

@@ -0,0 +1,4 @@
+{
+  "lhs": { "type": "string", "format": "uri" },
+  "rhs": { "type": "string" }
+}

tests/fixtures/format/format_unchanged.json

@@ -0,0 +1,4 @@
+{
+  "lhs": { "type": "string", "format": "date" },
+  "rhs": { "type": "string", "format": "date" }
+}

tests/snapshots/test__from_fixtures@format__format_add.json.snap

@@ -0,0 +1,20 @@
+---
+source: tests/test.rs
+assertion_line: 12
+expression: diff
+info:
+  lhs:
+    type: string
+  rhs:
+    format: email
+    type: string
+input_file: tests/fixtures/format/format_add.json
+---
+[
+    Change {
+        path: "",
+        change: FormatAdd {
+            added: "email",
+        },
+    },
+]

tests/snapshots/test__from_fixtures@format__format_change.json.snap

@@ -0,0 +1,22 @@
+---
+source: tests/test.rs
+assertion_line: 12
+expression: diff
+info:
+  lhs:
+    format: uuid
+    type: string
+  rhs:
+    format: date-time
+    type: string
+input_file: tests/fixtures/format/format_change.json
+---
+[
+    Change {
+        path: "",
+        change: FormatChange {
+            old_format: "uuid",
+            new_format: "date-time",
+        },
+    },
+]

tests/snapshots/test__from_fixtures@format__format_remove.json.snap

@@ -0,0 +1,20 @@
+---
+source: tests/test.rs
+assertion_line: 12
+expression: diff
+info:
+  lhs:
+    format: uri
+    type: string
+  rhs:
+    type: string
+input_file: tests/fixtures/format/format_remove.json
+---
+[
+    Change {
+        path: "",
+        change: FormatRemove {
+            removed: "uri",
+        },
+    },
+]

tests/snapshots/test__from_fixtures@format__format_unchanged.json.snap

@@ -0,0 +1,14 @@
+---
+source: tests/test.rs
+assertion_line: 12
+expression: diff
+info:
+  lhs:
+    format: date
+    type: string
+  rhs:
+    format: date
+    type: string
+input_file: tests/fixtures/format/format_unchanged.json
+---
+[]