feat: match metaschema with or without empty fragment

Author: kylef

CHANGELOG.md

@@ -12,6 +12,12 @@
   error will now be thrown instead of the schema being silently treated as a
   draft 4 schema.
 
+### Enhancements
+
+- `$schema` matching will now operate on normalise URIs and thus will handle
+  cases when the meta spec or the `$schema` URI both contain and don't contain
+  empty trailing fragments as the same meta schema.
+
 ## 0.6.0
 
 ### Breaking Changes

Sources/JSONSchema.swift

@@ -73,23 +73,23 @@ func validator(for schema: [String: Any]) throws -> Validator {
     throw ReferenceError.notFound
   }
 
-  if let id = DRAFT_2020_12_META_SCHEMA["$id"] as? String, schemaURI == id {
+  if let id = DRAFT_2020_12_META_SCHEMA["$id"] as? String, urlEqual(schemaURI, id) {
     return Draft202012Validator(schema: schema)
   }
 
-  if let id = DRAFT_2019_09_META_SCHEMA["$id"] as? String, schemaURI == id {
+  if let id = DRAFT_2019_09_META_SCHEMA["$id"] as? String, urlEqual(schemaURI, id) {
     return Draft201909Validator(schema: schema)
   }
 
-  if let id = DRAFT_07_META_SCHEMA["$id"] as? String, schemaURI == id {
+  if let id = DRAFT_07_META_SCHEMA["$id"] as? String, urlEqual(schemaURI, id) {
     return Draft7Validator(schema: schema)
   }
 
-  if let id = DRAFT_06_META_SCHEMA["$id"] as? String, schemaURI == id {
+  if let id = DRAFT_06_META_SCHEMA["$id"] as? String, urlEqual(schemaURI, id) {
     return Draft6Validator(schema: schema)
   }
 
-  if let id = DRAFT_04_META_SCHEMA["id"] as? String, schemaURI == id {
+  if let id = DRAFT_04_META_SCHEMA["id"] as? String, urlEqual(schemaURI, id) {
     return Draft4Validator(schema: schema)
   }
 

Sources/RefResolver.swift

@@ -32,6 +32,11 @@ func urlNormalise(_ value: String) -> String {
 }
 
 
+func urlEqual(_ lhs: String, _ rhs: String) -> Bool {
+  return urlNormalise(lhs) == urlNormalise(rhs)
+}
+
+
 class RefResolver {
   let referrer: [String: Any]
   var store: [String: Any]

Tests/JSONSchemaTests/JSONSchemaTests.swift

@@ -118,26 +118,51 @@ class ValidateTests: XCTestCase {
     XCTAssertTrue(result is Draft4Validator, "Unexpected type of validator \(result)")
   }
 
+  func testDraft4ValidatorIsAvailableWithoutFragment() throws {
+    let result = try validator(for: ["$schema": "http://json-schema.org/draft-04/schema"])
+    XCTAssertTrue(result is Draft4Validator, "Unexpected type of validator \(result)")
+  }
+
   func testDraft6ValidatorIsAvailable() throws {
     let result = try validator(for: ["$schema": "http://json-schema.org/draft-06/schema#"])
     XCTAssertTrue(result is Draft6Validator, "Unexpected type of validator \(result)")
   }
 
+  func testDraft6ValidatorIsAvailableWithoutFragment() throws {
+    let result = try validator(for: ["$schema": "http://json-schema.org/draft-06/schema"])
+    XCTAssertTrue(result is Draft6Validator, "Unexpected type of validator \(result)")
+  }
+
   func testDraft7ValidatorIsAvailable() throws {
     let result = try validator(for: ["$schema": "http://json-schema.org/draft-07/schema#"])
     XCTAssertTrue(result is Draft7Validator, "Unexpected type of validator \(result)")
   }
 
+  func testDraft7ValidatorIsAvailableWithoutFragment() throws {
+    let result = try validator(for: ["$schema": "http://json-schema.org/draft-07/schema"])
+    XCTAssertTrue(result is Draft7Validator, "Unexpected type of validator \(result)")
+  }
+
   func testDraft201909ValidatorIsAvailable() throws {
     let result = try validator(for: ["$schema": "https://json-schema.org/draft/2019-09/schema"])
     XCTAssertTrue(result is Draft201909Validator, "Unexpected type of validator \(result)")
   }
 
+  func testDraft201909ValidatorIsAvailableWithTrailingFragment() throws {
+    let result = try validator(for: ["$schema": "https://json-schema.org/draft/2019-09/schema#"])
+    XCTAssertTrue(result is Draft201909Validator, "Unexpected type of validator \(result)")
+  }
+
   func testDraft202012ValidatorIsAvailable() throws {
     let result = try validator(for: ["$schema": "https://json-schema.org/draft/2020-12/schema"])
     XCTAssertTrue(result is Draft202012Validator, "Unexpected type of validator \(result)")
   }
 
+  func testDraft202012ValidatorIsAvailableWithTrailingFragment() throws {
+    let result = try validator(for: ["$schema": "https://json-schema.org/draft/2020-12/schema#"])
+    XCTAssertTrue(result is Draft202012Validator, "Unexpected type of validator \(result)")
+  }
+
   func testUnknownValidator() throws {
     XCTAssertThrowsError(
       try validator(for: ["$schema": "https://example.com/schema"])