Allow caller to use type inferrence when calling HTTPSCallable functions

Signed-off-by: Peter Friese <[email protected]>

Author: peterfriese

FirebaseFunctionsSwift/Sources/Codable/Callable+Codable.swift

@@ -36,6 +36,25 @@ public extension Functions {
     -> Callable<Request, Response> {
     return Callable(callable: httpsCallable(name), encoder: encoder, decoder: decoder)
   }
+
+  /// Creates a reference to the Callable HTTPS trigger with the given name. The types of the `Encodable`
+  /// request and tyhe `Decodable` response will be inferred by the compiler.
+  ///
+  /// At the call site, use the following syntax:
+  ///
+  ///     let greeter: Callable<DataTestRequest, DataTestResponse> = functions.httpsCallable("greeter")
+  ///     try greeter(data) { result in
+  ///       print(result.greeting)
+  ///     }
+  ///
+  /// - Parameters:
+  ///   - name: The name of the Callable HTTPS trigger
+  func httpsCallable<Request, Response>(_ name: String,
+                                        encoder: StructureEncoder = StructureEncoder(),
+                                        decoder: StructureDecoder = StructureDecoder())
+    -> Callable<Request, Response> where Request: Encodable, Response: Decodable {
+    return Callable(callable: httpsCallable(name), encoder: encoder, decoder: decoder)
+  }
 }
 
 /**

FirebaseFunctionsSwift/Tests/IntegrationTests.swift

@@ -587,4 +587,58 @@ class IntegrationTests: XCTestCase {
       XCTAssertEqual(response, expected)
     }
   #endif
+
+  func testInferredTypes() throws {
+    let expectation = expectation(description: #function)
+    let data = DataTestRequest(
+      bool: true,
+      int: 2,
+      long: 9_876_543_210,
+      string: "four",
+      array: [5, 6],
+      null: nil
+    )
+    let function: Callable<DataTestRequest, DataTestResponse> = functions.httpsCallable("dataTest")
+
+    try function(data) { result in
+      do {
+        let response = try result.get()
+        let expected = DataTestResponse(
+          message: "stub response",
+          long: 420,
+          code: 42
+        )
+        XCTAssertEqual(response, expected)
+        expectation.fulfill()
+      } catch {
+        XCTAssert(false, "Failed to unwrap the function result: \(error)")
+      }
+    }
+    waitForExpectations(timeout: 5)
+  }
+
+  #if compiler(>=5.5) && canImport(_Concurrency)
+    @available(iOS 15, tvOS 15, macOS 12, watchOS 8, *)
+    func testInferredTyesAsync() async throws {
+      let data = DataTestRequest(
+        bool: true,
+        int: 2,
+        long: 9_876_543_210,
+        string: "four",
+        array: [5, 6],
+        null: nil
+      )
+
+      let function: Callable<DataTestRequest, DataTestResponse> = functions
+        .httpsCallable("dataTest")
+
+      let response = try await function(data)
+      let expected = DataTestResponse(
+        message: "stub response",
+        long: 420,
+        code: 42
+      )
+      XCTAssertEqual(response, expected)
+    }
+  #endif
 }