asyncLazySequence: harmonize unit tests nomenclature (#190)

Author: twittemb

Tests/AsyncAlgorithmsTests/TestLazy.swift

@@ -13,97 +13,102 @@
 import AsyncAlgorithms
 
 final class TestLazy: XCTestCase {
-  func test_array() async {
-    let source = [1, 2, 3, 4]
-    let expected = source
-    let sequence = source.async
-    
-    var actual = [Int]()
+  func test_lazy_outputs_elements_and_finishes_when_source_is_array() async {
+    let expected = [1, 2, 3, 4]
+    let sequence = expected.async
+
+    var collected = [Int]()
     for await item in sequence {
-      actual.append(item)
+      collected.append(item)
     }
 
-    XCTAssertEqual(expected, actual)
+    XCTAssertEqual(expected, collected)
   }
 
-  func test_set() async {
-    let source: Set = [1, 2, 3, 4]
-    let expected = source
-    let sequence = source.async
+  func test_lazy_outputs_elements_and_finishes_when_source_is_set() async {
+    let expected: Set = [1, 2, 3, 4]
+    let sequence = expected.async
 
-    var actual = Set<Int>()
+    var collected = Set<Int>()
     for await item in sequence {
-      actual.insert(item)
+      collected.insert(item)
     }
 
-    XCTAssertEqual(expected, actual)
+    XCTAssertEqual(expected, collected)
   }
 
-  func test_empty() async {
-    let source = EmptyCollection<Int>()
+  func test_lazy_finishes_without_elements_when_source_is_empty() async {
     let expected = [Int]()
-    let sequence = source.async
+    let sequence = expected.async
 
-    var actual = [Int]()
+    var collected = [Int]()
     for await item in sequence {
-      actual.append(item)
+      collected.append(item)
     }
 
-    XCTAssertEqual(expected, actual)
+    XCTAssertEqual(expected, collected)
   }
 
-  func test_iteration() async {
-    let source = ReportingSequence([1, 2, 3])
+  func test_lazy_triggers_expected_iterator_events_when_source_is_iterated() async {
+    let expected = [1, 2, 3]
+    let expectedEvents = [
+      ReportingSequence<Int>.Event.makeIterator,
+      .next,
+      .next,
+      .next,
+      .next
+    ]
+    let source = ReportingSequence(expected)
     let sequence = source.async
+
     XCTAssertEqual(source.events, [])
+
     var collected = [Int]()
     for await item in sequence {
       collected.append(item)
     }
-    XCTAssertEqual(collected, [1, 2, 3])
-    XCTAssertEqual(source.events, [
-      .makeIterator,
+
+    XCTAssertEqual(expected, collected)
+    XCTAssertEqual(expectedEvents, source.events)
+  }
+  
+  func test_lazy_stops_triggering_iterator_events_when_source_is_pastEnd() async {
+    let expected = [1, 2, 3]
+    let expectedEvents = [
+      ReportingSequence<Int>.Event.makeIterator,
       .next,
       .next,
       .next,
       .next
-    ])
-  }
-  
-  func test_manual_iteration() async {
-    let source = ReportingSequence([1, 2, 3])
+    ]
+    let source = ReportingSequence(expected)
     let sequence = source.async
+
     XCTAssertEqual(source.events, [])
+
     var collected = [Int]()
     var iterator = sequence.makeAsyncIterator()
     while let item = await iterator.next() {
       collected.append(item)
     }
-    XCTAssertEqual(collected, [1, 2, 3])
-    XCTAssertEqual(source.events, [
-      .makeIterator,
-      .next,
-      .next,
-      .next,
-      .next
-    ])
+
+    XCTAssertEqual(expected, collected)
+    XCTAssertEqual(expectedEvents, source.events)
+
     let pastEnd = await iterator.next()
+
     XCTAssertEqual(pastEnd, nil)
     // ensure that iterating past the end does not invoke next again
-    XCTAssertEqual(source.events, [
-      .makeIterator,
-      .next,
-      .next,
-      .next,
-      .next
-    ])
+    XCTAssertEqual(expectedEvents, source.events)
   }
 
-  func test_cancellation() async {
-    let source = Indefinite(value: "test")
-    let sequence = source.async
+  func test_lazy_finishes_when_task_is_cancelled() async {
     let finished = expectation(description: "finished")
     let iterated = expectation(description: "iterated")
+
+    let source = Indefinite(value: "test")
+    let sequence = source.async
+
     let task = Task {
       var firstIteration = false
       for await _ in sequence {
@@ -114,11 +119,14 @@ final class TestLazy: XCTestCase {
       }
       finished.fulfill()
     }
+
     // ensure the other task actually starts
     wait(for: [iterated], timeout: 1.0)
+
     // cancellation should ensure the loop finishes
     // without regards to the remaining underlying sequence
     task.cancel()
+
     wait(for: [finished], timeout: 1.0)
   }
 }