Fixes #276 - Unknown configuration options should throw an error (#297)

Author: PARAIPAN9

Sources/_OpenAPIGeneratorCore/Parser/YamsParser.swift

@@ -19,7 +19,27 @@ import Yams
 
 /// A parser that uses the Yams library to parse the provided
 /// raw file into an OpenAPI document.
-struct YamsParser: ParserProtocol {
+public struct YamsParser: ParserProtocol {
+
+    /// Extracts the top-level keys from a YAML string.
+    ///
+    /// - Parameter yamlString: The YAML string from which to extract keys.
+    /// - Returns: An array of top-level keys as strings.
+    /// - Throws: An error if there are any issues with parsing the YAML string.
+    public static func extractTopLevelKeys(fromYAMLString yamlString: String) throws -> [String] {
+        var yamlKeys = [String]()
+        let parser = try Parser(yaml: yamlString)
+
+        if let rootNode = try parser.singleRoot(),
+            case let .mapping(mapping) = rootNode
+        {
+            for (key, _) in mapping {
+                yamlKeys.append(key.string ?? "")
+            }
+        }
+        return yamlKeys
+    }
+
     func parseOpenAPI(
         _ input: InMemoryInputFile,
         config: Config,

Sources/swift-openapi-generator/GenerateOptions.swift

@@ -86,7 +86,20 @@ extension _GenerateOptions {
         if !featureFlag.isEmpty {
             return Set(featureFlag)
         }
-        return Set(config?.featureFlags ?? [])
+        return config?.featureFlags ?? []
+    }
+
+    /// Validates a collection of keys against a predefined set of allowed keys.
+    ///
+    /// - Parameter keys: A collection of keys to be validated.
+    /// - Throws: A `ValidationError` if any key in the collection is not found in the
+    ///           allowed set of keys specified by `_UserConfig.codingKeysRawValues`.
+    func validateKeys(_ keys: [String]) throws {
+        for key in keys {
+            if !_UserConfig.codingKeysRawValues.contains(key) {
+                throw ValidationError("Unknown configuration key found in config file: \(key)")
+            }
+        }
     }
 
     /// Returns the configuration requested by the user.
@@ -99,6 +112,16 @@ extension _GenerateOptions {
         }
         do {
             let data = try Data(contentsOf: config)
+            let configAsString = String(decoding: data, as: UTF8.self)
+            var yamlKeys = [String]()
+
+            do {
+                yamlKeys = try YamsParser.extractTopLevelKeys(fromYAMLString: configAsString)
+            } catch {
+                throw ValidationError("The config isn't valid. \(error)")
+            }
+            try validateKeys(yamlKeys)
+
             let config = try YAMLDecoder().decode(_UserConfig.self, from: data)
             return config
         } catch {

Sources/swift-openapi-generator/UserConfig.swift

@@ -29,4 +29,13 @@ struct _UserConfig: Codable {
 
     /// A set of features to explicitly enable.
     var featureFlags: FeatureFlags?
+
+    /// A set of raw values corresponding to the coding keys of this struct.
+    static let codingKeysRawValues = Set(CodingKeys.allCases.map({ $0.rawValue }))
+
+    enum CodingKeys: String, CaseIterable, CodingKey {
+        case generate
+        case additionalImports
+        case featureFlags
+    }
 }

Tests/OpenAPIGeneratorCoreTests/Parser/Test_YamsParser.swift

@@ -128,6 +128,38 @@ final class Test_YamsParser: Test_Core {
         assertThrownError(try _test(yaml), expectedDiagnostic: expected)
     }
 
+    func testExtractTopLevelKeysWithValidYAML() {
+        let yaml = """
+            generate:
+              - types
+              - server
+
+            featureFlags:
+              - nullableSchemas
+
+            additionalImports:
+              - Foundation
+            """
+        let keys = try? YamsParser.extractTopLevelKeys(fromYAMLString: yaml)
+        XCTAssertEqual(keys, ["generate", "featureFlags", "additionalImports"])
+    }
+
+    func testExtractTopLevelKeysWithInvalidYAML() {
+        // `additionalImports` is missing `:` at the end.
+        let yaml = """
+            generate:
+              - types
+              - server
+
+            featureFlags:
+              - nullableSchemas
+
+            additionalImports
+              - Foundation
+            """
+        XCTAssertThrowsError(try YamsParser.extractTopLevelKeys(fromYAMLString: yaml))
+    }
+
     private func _test(_ yaml: String) throws -> ParsedOpenAPIRepresentation {
         try YamsParser()
             .parseOpenAPI(