Add DisposeBag function builder + tests

RxSwift/Disposables/DisposeBag.swift

@@ -84,13 +84,18 @@ public final class DisposeBag: DisposeBase {
 }
 
 extension DisposeBag {
-
     /// Convenience init allows a list of disposables to be gathered for disposal.
     public convenience init(disposing disposables: Disposable...) {
         self.init()
         self._disposables += disposables
     }
 
+    /// Convenience init which utilizes a function builder to let you pass in a list of
+    /// disposables to make a DisposeBag of.
+    public convenience init(@DisposableBuilder builder: () -> [Disposable]) {
+      self.init(disposing: builder())
+    }
+
     /// Convenience init allows an array of disposables to be gathered for disposal.
     public convenience init(disposing disposables: [Disposable]) {
         self.init()
@@ -111,4 +116,12 @@ extension DisposeBag {
             self._disposables += disposables
         }
     }
+
+    /// A function builder accepting a list of Disposables and returning them as an array.
+    @_functionBuilder
+    public struct DisposableBuilder {
+      public static func buildBlock(_ disposables: Disposable...) -> [Disposable] {
+        return disposables
+      }
+    }
 }

Sources/AllTestz/main.swift

@@ -218,6 +218,7 @@ final class DisposeBagTest_ : DisposeBagTest, RxTestCase {
     ("testDisposeBagInsert", DisposeBagTest.testDisposeBagInsert),
     ("testDisposeBagVaradicInsert", DisposeBagTest.testDisposeBagVaradicInsert),
     ("testDisposeBagVaradicInsertArray", DisposeBagTest.testDisposeBagVaradicInsertArray),
+    ("testDisposableBuilder", DisposeBagTest.testDisposableBuilder),
     ] }
 }
 

Tests/RxSwiftTests/DisposeBagTest.swift

@@ -43,7 +43,6 @@ extension DisposeBagTest {
 
 // DisposeBag bag test
 extension DisposeBagTest {
-
     func testDisposeBagVaradicInsert() {
         let disposable1 = TestDisposable()
         let disposable2 = TestDisposable()
@@ -73,7 +72,32 @@ extension DisposeBagTest {
         XCTAssert(disposable1.count == 1)
         XCTAssert(disposable2.count == 1)
     }
+}
 
+// DisposeBag function builder initializer tests
+extension DisposeBagTest {
+  func testDisposableBuilder() {
+    let disposable1 = TestDisposable()
+    let disposable2 = TestDisposable()
+    let disposable3 = TestDisposable()
+
+    var disposeBag = DisposeBag {
+      disposable1
+      disposable2
+      disposable3
+    }
+
+    XCTAssert(disposable1.count == 0)
+    XCTAssert(disposable2.count == 0)
+    XCTAssert(disposable3.count == 0)
+    disposeBag = DisposeBag()
+    XCTAssert(disposable1.count == 1)
+    XCTAssert(disposable2.count == 1)
+    XCTAssert(disposable3.count == 1)
+
+    // Avoids "Variable 'disposeBag' was written to, but never read"
+    _ = disposeBag
+  }
 }
 
 private class TestDisposable: Disposable {