Make range support a count of 0

ReactiveX · Feb 7, 2019 · 268ccda · 268ccda
1 parent 9404f89
commit 268ccda
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Showing 3 changed files with 15 additions and 2 deletions.
diff --git a/RxSwift/Observables/Range.swift b/RxSwift/Observables/Range.swift
@@ -28,11 +28,11 @@ final private class RangeProducer<E: RxAbstractInteger>: Producer<E> {
     fileprivate let _scheduler: ImmediateSchedulerType
 
     init(start: E, count: E, scheduler: ImmediateSchedulerType) {
-        if count < 0 {
+        guard count >= 0 else {
             rxFatalError("count can't be negative")
         }
 
-        if start &+ (count - 1) < start {
+        guard start &+ (count - 1) >= start || count == 0 else {
             rxFatalError("overflow of count")
         }
 

diff --git a/Sources/AllTestz/main.swift b/Sources/AllTestz/main.swift
@@ -1097,6 +1097,7 @@ final class ObservableRangeTest_ : ObservableRangeTest, RxTestCase {
 
     static var allTests: [(String, (ObservableRangeTest_) -> () -> Void)] { return [
     ("testRange_Boundaries", ObservableRangeTest.testRange_Boundaries),
+    ("testRange_ZeroCount", ObservableRangeTest.testRange_ZeroCount),
     ("testRange_Dispose", ObservableRangeTest.testRange_Dispose),
     ] }
 }

diff --git a/Tests/RxSwiftTests/Observable+RangeTests.swift b/Tests/RxSwiftTests/Observable+RangeTests.swift
@@ -27,6 +27,18 @@ extension ObservableRangeTest {
             ])
     }
 
+    func testRange_ZeroCount() {
+        let scheduler = TestScheduler(initialClock: 0)
+
+        let res = scheduler.start {
+            Observable.range(start: 0, count: 0, scheduler: scheduler)
+        }
+
+        XCTAssertEqual(res.events, [
+            .completed(201)
+            ])
+    }
+
     func testRange_Dispose() {
         let scheduler = TestScheduler(initialClock: 0)