Add support for schemas with only federated resolvers

.github/workflows/build.yml

@@ -32,41 +32,38 @@ jobs:
         xcode-version: latest-stable
     - uses: actions/checkout@v3
     - name: Build and test
-      run: swift test --parallel --enable-test-discovery
+      run: swift test --parallel
 
   linux:
-    name: Test on Linux
+    name: Test Swift ${{ matrix.swift }}
     runs-on: ubuntu-latest
-    steps:
-    - uses: swift-actions/setup-swift@v2
-    - uses: actions/checkout@v3
-    - name: Test
-      run: swift test --parallel --enable-code-coverage
-    - name: Get test coverage html
-      run: |
-        llvm-cov show \
-          $(swift build --show-bin-path)/GraphitiPackageTests.xctest \
-          --instr-profile $(swift build --show-bin-path)/codecov/default.profdata \
-          --ignore-filename-regex="\.build|Tests" \
-          --format html \
-          --output-dir=.test-coverage
-    - name: Upload test coverage html
-      uses: actions/upload-artifact@v3
-      with:
-        name: test-coverage-report
-        path: .test-coverage
-
-  backcompat-ubuntu-22_04:
-    name: Test Swift ${{ matrix.swift }} on Ubuntu 22.04
-    runs-on: ubuntu-22.04
+    container:
+      image: swift:${{ matrix.swift }}
     strategy:
       matrix:
-        swift: ["5.8", "5.9", "5.10"]
+        swift: ["5.8", "5.9", "5.10", "6.0", "6.1"]
     steps:
-    - uses: swift-actions/setup-swift@v2
-      with:
-        swift-version: ${{ matrix.swift }}
     - uses: actions/checkout@v3
     - name: Test
       run: swift test --parallel
 
+  # TODO: Add test coverage upload but it's currently not working with Swift 6.1.0/Ubuntu-latest
+  # test-coverage:
+  #   runs-on: ubuntu-latest
+  #   steps:
+  #   - uses: actions/checkout@v3
+  #   - name: Test
+  #     run: swift test --parallel --enable-code-coverage
+  #   - name: Get test coverage html
+  #     run: |
+  #       llvm-cov show \
+  #         $(swift build --show-bin-path)/GraphitiPackageTests.xctest \
+  #         --instr-profile $(swift build --show-bin-path)/codecov/default.profdata \
+  #         --ignore-filename-regex="\.build|Tests" \
+  #         --format html \
+  #         --output-dir=.test-coverage
+  #   - name: Upload test coverage html
+  #     uses: actions/upload-artifact@v4
+  #     with:
+  #       name: test-coverage-report
+  #       path: .test-coverage

Sources/Graphiti/Federation/Key/Type+Key.swift

@@ -1,14 +1,14 @@
 import GraphQL
 
 public extension Type {
-    @discardableResult
     /// Define and add the federated key to this type.
     ///
     /// For more information, see https://www.apollographql.com/docs/federation/entities
     /// - Parameters:
     ///   - function: The resolver function used to load this entity based on the key value.
     ///   - _:  The key value. The name of this argument must match a Type field.
     /// - Returns: Self for chaining.
+    @discardableResult
     func key<Arguments: Codable>(
         at function: @escaping AsyncResolve<Resolver, Context, Arguments, ObjectType?>,
         @ArgumentComponentBuilder<Arguments> _ argument: () -> ArgumentComponent<Arguments>
@@ -17,14 +17,14 @@ public extension Type {
         return self
     }
 
-    @discardableResult
     /// Define and add the federated key to this type.
     ///
     /// For more information, see https://www.apollographql.com/docs/federation/entities
     /// - Parameters:
     ///   - function: The resolver function used to load this entity based on the key value.
     ///   - _:  The key values. The names of these arguments must match Type fields.
     /// - Returns: Self for chaining.
+    @discardableResult
     func key<Arguments: Codable>(
         at function: @escaping AsyncResolve<Resolver, Context, Arguments, ObjectType?>,
         @ArgumentComponentBuilder<Arguments> _ arguments: ()
@@ -34,14 +34,14 @@ public extension Type {
         return self
     }
 
-    @discardableResult
     /// Define and add the federated key to this type.
     ///
     /// For more information, see https://www.apollographql.com/docs/federation/entities
     /// - Parameters:
     ///   - function: The resolver function used to load this entity based on the key value.
     ///   - _:  The key value. The name of this argument must match a Type field.
     /// - Returns: Self for chaining.
+    @discardableResult
     func key<Arguments: Codable>(
         at function: @escaping SimpleAsyncResolve<Resolver, Context, Arguments, ObjectType?>,
         @ArgumentComponentBuilder<Arguments> _ argument: () -> ArgumentComponent<Arguments>
@@ -50,14 +50,14 @@ public extension Type {
         return self
     }
 
-    @discardableResult
     /// Define and add the federated key to this type.
     ///
     /// For more information, see https://www.apollographql.com/docs/federation/entities
     /// - Parameters:
     ///   - function: The resolver function used to load this entity based on the key value.
     ///   - _:  The key values. The names of these arguments must match Type fields.
     /// - Returns: Self for chaining.
+    @discardableResult
     func key<Arguments: Codable>(
         at function: @escaping SimpleAsyncResolve<Resolver, Context, Arguments, ObjectType?>,
         @ArgumentComponentBuilder<Arguments> _ arguments: ()
@@ -67,14 +67,14 @@ public extension Type {
         return self
     }
 
-    @discardableResult
     /// Define and add the federated key to this type.
     ///
     /// For more information, see https://www.apollographql.com/docs/federation/entities
     /// - Parameters:
     ///   - function: The resolver function used to load this entity based on the key value.
     ///   - _:  The key value. The name of this argument must match a Type field.
     /// - Returns: Self for chaining.
+    @discardableResult
     func key<Arguments: Codable>(
         at function: @escaping SyncResolve<Resolver, Context, Arguments, ObjectType?>,
         @ArgumentComponentBuilder<Arguments> _ arguments: ()
@@ -84,14 +84,14 @@ public extension Type {
         return self
     }
 
-    @discardableResult
     /// Define and add the federated key to this type.
     ///
     /// For more information, see https://www.apollographql.com/docs/federation/entities
     /// - Parameters:
     ///   - function: The resolver function used to load this entity based on the key value.
     ///   - _:  The key values. The names of these arguments must match Type fields.
     /// - Returns: Self for chaining.
+    @discardableResult
     func key<Arguments: Codable>(
         at function: @escaping SyncResolve<Resolver, Context, Arguments, ObjectType?>,
         @ArgumentComponentBuilder<Arguments> _ argument: () -> ArgumentComponent<Arguments>
@@ -102,15 +102,15 @@ public extension Type {
 }
 
 public extension Type {
-    @available(macOS 10.15, iOS 15, watchOS 8, tvOS 15, *)
-    @discardableResult
     /// Define and add the federated key to this type.
     ///
     /// For more information, see https://www.apollographql.com/docs/federation/entities
     /// - Parameters:
     ///   - function: The resolver function used to load this entity based on the key value.
     ///   - _:  The key value. The name of this argument must match a Type field.
     /// - Returns: Self for chaining.
+    @available(macOS 10.15, iOS 15, watchOS 8, tvOS 15, *)
+    @discardableResult
     func key<Arguments: Codable>(
         at function: @escaping ConcurrentResolve<Resolver, Context, Arguments, ObjectType?>,
         @ArgumentComponentBuilder<Arguments> _ argument: () -> ArgumentComponent<Arguments>
@@ -119,15 +119,15 @@ public extension Type {
         return self
     }
 
-    @available(macOS 10.15, iOS 15, watchOS 8, tvOS 15, *)
-    @discardableResult
     /// Define and add the federated key to this type.
     ///
     /// For more information, see https://www.apollographql.com/docs/federation/entities
     /// - Parameters:
     ///   - function: The resolver function used to load this entity based on the key value.
     ///   - _:  The key values. The names of these arguments must match Type fields.
     /// - Returns: Self for chaining.
+    @available(macOS 10.15, iOS 15, watchOS 8, tvOS 15, *)
+    @discardableResult
     func key<Arguments: Codable>(
         at function: @escaping ConcurrentResolve<Resolver, Context, Arguments, ObjectType?>,
         @ArgumentComponentBuilder<Arguments> _ arguments: () -> [ArgumentComponent<Arguments>]

Sources/Graphiti/Schema/Schema.swift

@@ -1,6 +1,10 @@
 import GraphQL
 import NIO
 
+public struct SchemaError: Error, Equatable {
+    let description: String
+}
+
 public final class Schema<Resolver, Context> {
     public let schema: GraphQLSchema
 
@@ -16,11 +20,14 @@ public final class Schema<Resolver, Context> {
             try component.update(typeProvider: typeProvider, coders: coders)
         }
 
-        guard let query = typeProvider.query else {
-            fatalError("Query type is required.")
+        guard typeProvider.query != nil || !typeProvider.federatedResolvers.isEmpty else {
+            throw SchemaError(
+                description: "Schema must contain at least 1 query or federated resolver"
+            )
         }
+
         schema = try GraphQLSchema(
-            query: query,
+            query: typeProvider.query,
             mutation: typeProvider.mutation,
             subscription: typeProvider.subscription,
             types: typeProvider.types,

Sources/Graphiti/SchemaBuilders/SchemaBuilder.swift

@@ -27,19 +27,19 @@ public final class SchemaBuilder<Resolver, Context> {
         subscriptionFields = []
     }
 
-    @discardableResult
     /// Allows for setting API encoders and decoders with customized settings.
     /// - Parameter newCoders: The new coders to use
     /// - Returns: This object for method chaining
+    @discardableResult
     public func setCoders(to newCoders: Coders) -> Self {
         coders = newCoders
         return self
     }
 
-    @discardableResult
     /// Allows for setting SDL for federated subgraphs.
     /// - Parameter newSDL: The new SDL to use
     /// - Returns: This object for method chaining
+    @discardableResult
     public func setFederatedSDL(to newSDL: String) -> Self {
         federatedSDL = newSDL
         return self
@@ -63,10 +63,10 @@ public final class SchemaBuilder<Resolver, Context> {
         return self
     }
 
-    @discardableResult
     /// Adds multiple query operation definitions to the schema.
     /// - Parameter component: The query operations to add
     /// - Returns: This object for method chaining
+    @discardableResult
     public func add(
         @TypeComponentBuilder<Resolver, Context> _ components: ()
             -> [TypeComponent<Resolver, Context>]
@@ -77,10 +77,10 @@ public final class SchemaBuilder<Resolver, Context> {
         return self
     }
 
-    @discardableResult
     /// Adds multiple query operation definitions to the schema.
     /// - Parameter component: The query operations to add
     /// - Returns: This object for method chaining
+    @discardableResult
     public func addQuery(
         @FieldComponentBuilder<Resolver, Context> _ fields: ()
             -> [FieldComponent<Resolver, Context>]
@@ -91,10 +91,10 @@ public final class SchemaBuilder<Resolver, Context> {
         return self
     }
 
-    @discardableResult
     /// Adds multiple mutation operation definitions to the schema.
     /// - Parameter component: The query operations to add
     /// - Returns: This object for method chaining
+    @discardableResult
     public func addMutation(
         @FieldComponentBuilder<Resolver, Context> _ fields: ()
             -> [FieldComponent<Resolver, Context>]
@@ -105,10 +105,10 @@ public final class SchemaBuilder<Resolver, Context> {
         return self
     }
 
-    @discardableResult
     /// Adds multiple subscription operation definitions to the schema.
     /// - Parameter component: The query operations to add
     /// - Returns: This object for method chaining
+    @discardableResult
     public func addSubscription(
         @FieldComponentBuilder<Resolver, Context> _ fields: ()
             -> [FieldComponent<Resolver, Context>]
@@ -119,10 +119,10 @@ public final class SchemaBuilder<Resolver, Context> {
         return self
     }
 
-    @discardableResult
     /// Adds multiple type, query, mutation, and subscription definitions using partial schemas to the schema.
     /// - Parameter partials: Partial schemas that declare types, query, mutation, and/or subscription definiton
     /// - Returns: Thie object for method chaining
+    @discardableResult
     public func use(partials: [PartialSchema<Resolver, Context>]) -> Self {
         for type in partials.flatMap({ $0.types }) {
             typeComponents.append(type)