refactor: make validations throwable

This is to allow us to throw errors in future from these code paths

Author: kylef

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## Master
 
+### Breaking Changes
+
+- The validation API may now throw errors if the provided JSON Schema is
+  invalid.
+
 ### Enhancements
 
 - The failing required validation error message is now emitted for each

README.md

@@ -18,7 +18,7 @@ pod 'JSONSchema'
 ```swift
 import JSONSchema
 
-JSONSchema.validate(["name": "Eggs", "price": 34.99], schema: [
+try JSONSchema.validate(["name": "Eggs", "price": 34.99], schema: [
   "type": "object",
   "properties": [
     "name": ["type": "string"],
@@ -34,7 +34,7 @@ Validate returns an enumeration `ValidationResult` which contains all
 validation errors.
 
 ```python
-print(validate(["price": 34.99], schema: ["required": ["name"]]).errors)
+print(try validate(["price": 34.99], schema: ["required": ["name"]]).errors)
 >>> "Required property 'name' is missing."
 ```
 

Sources/Core/ref.swift

@@ -5,7 +5,7 @@ func ref(context: Context, reference: Any, instance: Any, schema: [String: Any])
 
   guard let document = context.resolve(ref: reference) else {
     return AnySequence([
-      ValidationError("Reference not found '\(reference)'"),
+      ValidationError("Reference not found '\(reference)'", instanceLocation: nil),
     ])
   }
 

Sources/JSONSchema.swift

@@ -51,14 +51,14 @@ public struct Schema {
     self.schema = schema
   }
 
-  public func validate(_ data: Any) -> ValidationResult {
+  public func validate(_ data: Any) throws -> ValidationResult {
     let validator = JSONSchema.validator(for: schema)
-    return validator.validate(instance: data)
+    return try validator.validate(instance: data)
   }
 
-  public func validate(_ data: Any) -> AnySequence<ValidationError> {
+  public func validate(_ data: Any) throws -> AnySequence<ValidationError> {
     let validator = JSONSchema.validator(for: schema)
-    return validator.validate(instance: data)
+    return try validator.validate(instance: data)
   }
 }
 
@@ -84,12 +84,12 @@ func validator(for schema: [String: Any]) -> Validator {
 }
 
 
-public func validate(_ value: Any, schema: [String: Any]) -> ValidationResult {
-  return validator(for: schema).validate(instance: value)
+public func validate(_ value: Any, schema: [String: Any]) throws -> ValidationResult {
+  return try validator(for: schema).validate(instance: value)
 }
 
 
-public func validate(_ value: Any, schema: Bool) -> ValidationResult {
+public func validate(_ value: Any, schema: Bool) throws -> ValidationResult {
   let validator = Draft4Validator(schema: schema)
-  return validator.validate(instance: value)
+  return try validator.validate(instance: value)
 }

Sources/Validator.swift

@@ -64,12 +64,12 @@ protocol Validator {
 }
 
 extension Validator {
-  public func validate(instance: Any) -> ValidationResult {
+  public func validate(instance: Any) throws -> ValidationResult {
     let context = Context(resolver: resolver, validator: self)
     return context.validate(instance: instance, schema: schema).validationResult()
   }
 
-  public func validate(instance: Any) -> AnySequence<ValidationError> {
+  public func validate(instance: Any) throws -> AnySequence<ValidationError> {
     let context = Context(resolver: resolver, validator: self)
     return context.validate(instance: instance, schema: schema)
   }

Tests/JSONSchemaTests/JSONSchemaCases.swift

@@ -11,52 +11,52 @@ func JSONFixture(_ path: Path) throws -> [[String: Any]] {
 }
 
 
-func draft4Validator(schema: Any, instance: Any) -> ValidationResult {
+func draft4Validator(schema: Any, instance: Any) throws -> ValidationResult {
   if let schema = schema as? Bool {
-    return Draft4Validator(schema: schema).validate(instance: instance)
+    return try Draft4Validator(schema: schema).validate(instance: instance)
   }
 
   if let schema = schema as? [String: Any] {
-    return validate(instance, schema: schema)
+    return try validate(instance, schema: schema)
   }
 
   fatalError()
 }
 
 
-func draft6Validator(schema: Any, instance: Any) -> ValidationResult {
+func draft6Validator(schema: Any, instance: Any) throws -> ValidationResult {
   if let schema = schema as? Bool {
-    return Draft6Validator(schema: schema).validate(instance: instance)
+    return try Draft6Validator(schema: schema).validate(instance: instance)
   }
 
   if let schema = schema as? [String: Any] {
-    return Draft6Validator(schema: schema).validate(instance: instance)
+    return try Draft6Validator(schema: schema).validate(instance: instance)
   }
 
   fatalError()
 }
 
 
-func draft7Validator(schema: Any, instance: Any) -> ValidationResult {
+func draft7Validator(schema: Any, instance: Any) throws -> ValidationResult {
   if let schema = schema as? Bool {
-    return Draft7Validator(schema: schema).validate(instance: instance)
+    return try Draft7Validator(schema: schema).validate(instance: instance)
   }
 
   if let schema = schema as? [String: Any] {
-    return Draft7Validator(schema: schema).validate(instance: instance)
+    return try Draft7Validator(schema: schema).validate(instance: instance)
   }
 
   fatalError()
 }
 
 
-func draft201909Validator(schema: Any, instance: Any) -> ValidationResult {
+func draft201909Validator(schema: Any, instance: Any) throws -> ValidationResult {
   if let schema = schema as? Bool {
-    return Draft201909Validator(schema: schema).validate(instance: instance)
+    return try Draft201909Validator(schema: schema).validate(instance: instance)
   }
 
   if let schema = schema as? [String: Any] {
-    return Draft201909Validator(schema: schema).validate(instance: instance)
+    return try Draft201909Validator(schema: schema).validate(instance: instance)
   }
 
   fatalError()
@@ -174,7 +174,7 @@ class JSONSchemaCases: XCTestCase {
     ] + additionalExclusions)
   }
 
-  func test(name: String, validator: @escaping ((_ schema: Any, _ instance: Any) -> (ValidationResult)), excluding: [String]) throws {
+  func test(name: String, validator: @escaping ((_ schema: Any, _ instance: Any) throws -> (ValidationResult)), excluding: [String]) throws {
     let filePath = #file
     let path = Path(filePath) + ".." + ".." + "Cases" + "tests" + name
 
@@ -203,7 +203,7 @@ class JSONSchemaCases: XCTestCase {
 
     let flatCases = cases.reduce([Case](), +)
     for c in flatCases {
-      for (name, assertion) in makeAssertions(c, validator) {
+      for (_, assertion) in makeAssertions(c, validator) {
         // TODO: Improve testing
         assertion()
       }
@@ -244,16 +244,26 @@ func makeCase(_ filename: String) -> (_ object: [String: Any]) -> Case {
 typealias Assertion = (String, () -> ())
 
 
-func makeAssertions(_ c: Case, _ validator: @escaping ((_ schema: Any, _ instance: Any) -> (ValidationResult))) -> ([Assertion]) {
+func makeAssertions(_ c: Case, _ validator: @escaping ((_ schema: Any, _ instance: Any) throws -> (ValidationResult))) -> ([Assertion]) {
   return c.tests.map { test -> Assertion in
     let label = "\(c.description) \(test.description)"
     return (label, {
       let result: ValidationResult
 
       if let schema = c.schema as? [String: Any] {
-        result = validator(schema, test.data)
+        do {
+          result = try validator(schema, test.data)
+        } catch {
+          XCTFail(error.localizedDescription)
+          return
+        }
       } else if let schema = c.schema as? Bool {
-        result = validator(schema, test.data)
+        do {
+          result = try validator(schema, test.data)
+        } catch {
+          XCTFail(error.localizedDescription)
+          return
+        }
       } else {
         fatalError()
       }

Tests/JSONSchemaTests/JSONSchemaTests.swift

@@ -29,14 +29,14 @@ class JSONSchemaTests: XCTestCase {
   }
 
   func testSuccessfulValidation() {
-    XCTAssertTrue(schema.validate([String: Any]()).valid)
+    try XCTAssertTrue(schema.validate([String: Any]()).valid)
   }
 
   func testUnsuccessfulValidation() {
-    XCTAssertFalse(schema.validate([String]()).valid)
+    try XCTAssertFalse(schema.validate([String]()).valid)
   }
 
-  func testReadme() {
+  func testReadme() throws {
     let schema = Schema([
       "type": "object",
       "properties": [
@@ -46,11 +46,11 @@ class JSONSchemaTests: XCTestCase {
       "required": ["name"],
     ])
 
-    XCTAssertTrue(schema.validate(["name": "Eggs", "price": 34.99]).valid)
-    XCTAssertFalse(schema.validate(["price": 34.99]).valid)
+    try XCTAssertTrue(schema.validate(["name": "Eggs", "price": 34.99]).valid)
+    try XCTAssertFalse(schema.validate(["price": 34.99]).valid)
   }
 
-  func testIterableInterface() {
+  func testIterableInterface() throws {
     let schema = Schema([
       "type": "object",
       "properties": [
@@ -61,14 +61,14 @@ class JSONSchemaTests: XCTestCase {
     ])
 
     var counter = 0
-    for error in schema.validate(["price": 34.99]) {
+    for error in try schema.validate(["price": 34.99]) {
       XCTAssertEqual(error.description, "Required property 'name' is missing")
       counter += 1
     }
 
     XCTAssertEqual(counter, 1)
 
-    let result = Array(schema.validate(["price": 34.99]))
+    let result = try Array(schema.validate(["price": 34.99]))
 
     XCTAssertEqual(result.map(\.description), [
       "Required property 'name' is missing"
@@ -89,8 +89,8 @@ class ValidateTests: XCTestCase {
       "required": ["name"],
     ]
 
-    XCTAssertTrue(validate(["name": "Eggs", "price": 34.99], schema: schema).valid)
-    XCTAssertFalse(validate(["price": 34.99], schema: schema).valid)
+    try XCTAssertTrue(validate(["name": "Eggs", "price": 34.99], schema: schema).valid)
+    try XCTAssertFalse(validate(["price": 34.99], schema: schema).valid)
   }
 
   func testValidateDraft6() {
@@ -104,16 +104,16 @@ class ValidateTests: XCTestCase {
       "required": ["name"],
     ]
 
-    XCTAssertTrue(validate(["name": "Eggs", "price": 34.99], schema: schema).valid)
-    XCTAssertFalse(validate(["price": 34.99], schema: schema).valid)
+    try XCTAssertTrue(validate(["name": "Eggs", "price": 34.99], schema: schema).valid)
+    try XCTAssertFalse(validate(["price": 34.99], schema: schema).valid)
   }
 
   func testDraft6ValidatorIsAvailable() {
     let result = validator(for: ["$schema": "http://json-schema.org/draft-06/schema#"])
     XCTAssertTrue(result is Draft6Validator, "Unexpected type of validator \(result)")
   }
 
-  func testValidateDraft7() {
+  func testValidateDraft7() throws {
     let schema: [String: Any]  = [
       "$schema": "http://json-schema.org/draft-07/schema#",
       "type": "object",
@@ -124,17 +124,17 @@ class ValidateTests: XCTestCase {
       "required": ["name"],
     ]
 
-    XCTAssertTrue(validate(["name": "Eggs", "price": 34.99], schema: schema).valid)
-    XCTAssertFalse(validate(["price": 34.99], schema: schema).valid)
+    try XCTAssertTrue(validate(["name": "Eggs", "price": 34.99], schema: schema).valid)
+    try XCTAssertFalse(validate(["price": 34.99], schema: schema).valid)
   }
 
-  func testValidatesRequired() {
+  func testValidatesRequired() throws {
     let schema: [String: Any] = [
       "$schema": "http://json-schema.org/draft-07/schema#",
       "required": ["one", "two", "three"],
     ]
 
-    let result = validate(["one": true, "three": true], schema: schema)
+    let result = try validate(["one": true, "three": true], schema: schema)
 
     switch result {
     case .valid:
@@ -146,15 +146,15 @@ class ValidateTests: XCTestCase {
     }
   }
 
-  func testRequiredValidationLocation() {
+  func testRequiredValidationLocation() throws {
     let schema: [String: Any] = [
       "$schema": "http://json-schema.org/draft-07/schema#",
       "items": [
         "required": ["test"],
       ]
     ]
 
-    let result = validate([[:]], schema: schema)
+    let result = try validate([[:]], schema: schema)
 
     switch result {
     case .valid: