Merge pull request Quick#594 from Quick/setalgebra-beempty

Add `beEmpty` matcher for `SetAlgebra`

Sources/Nimble/Matchers/BeEmpty.swift

@@ -13,6 +13,17 @@ public func beEmpty<S: Sequence>() -> Predicate<S> {
     }
 }
 
+/// A Nimble matcher that succeeds when a value is "empty". For collections, this
+/// means the are no items in that collection. For strings, it is an empty string.
+public func beEmpty<S: SetAlgebra>() -> Predicate<S> {
+    return Predicate.simple("be empty") { actualExpression in
+        guard let actual = try actualExpression.evaluate() else {
+            return .fail
+        }
+        return PredicateStatus(bool: actual.isEmpty)
+    }
+}
+
 /// A Nimble matcher that succeeds when a value is "empty". For collections, this
 /// means the are no items in that collection. For strings, it is an empty string.
 public func beEmpty() -> Predicate<String> {

Tests/NimbleTests/Matchers/BeEmptyTest.swift

@@ -34,16 +34,12 @@ final class BeEmptyTest: XCTestCase, XCTestCaseProvider {
 
         expect("").to(beEmpty())
         expect("foo").toNot(beEmpty())
+
+        expect([] as TestOptionSet).to(beEmpty())
+        expect(TestOptionSet.one).toNot(beEmpty())
     }
 
     func testBeEmptyNegative() {
-        failsWithErrorMessageForNil("expected to be empty, got <nil>") {
-            expect(nil as NSString?).to(beEmpty())
-        }
-        failsWithErrorMessageForNil("expected to not be empty, got <nil>") {
-            expect(nil as [CInt]?).toNot(beEmpty())
-        }
-
         failsWithErrorMessage("expected to not be empty, got <()>") {
             expect(NSArray()).toNot(beEmpty())
         }
@@ -73,5 +69,49 @@ final class BeEmptyTest: XCTestCase, XCTestCaseProvider {
         failsWithErrorMessage("expected to be empty, got <foo>") {
             expect("foo").to(beEmpty())
         }
+
+        failsWithErrorMessage("expected to not be empty, got <TestOptionSet(rawValue: 0)>") {
+            expect([] as TestOptionSet).toNot(beEmpty())
+        }
+        failsWithErrorMessage("expected to be empty, got <TestOptionSet(rawValue: 1)>") {
+            expect(TestOptionSet.one).to(beEmpty())
+        }
+    }
+
+    func testNilMatches() {
+        failsWithErrorMessageForNil("expected to be empty, got <nil>") {
+            expect(nil as NSString?).to(beEmpty())
+        }
+        failsWithErrorMessageForNil("expected to not be empty, got <nil>") {
+            expect(nil as NSString?).toNot(beEmpty())
+        }
+
+        failsWithErrorMessageForNil("expected to be empty, got <nil>") {
+            expect(nil as [CInt]?).to(beEmpty())
+        }
+        failsWithErrorMessageForNil("expected to not be empty, got <nil>") {
+            expect(nil as [CInt]?).toNot(beEmpty())
+        }
+
+        failsWithErrorMessageForNil("expected to be empty, got <nil>") {
+            expect(nil as TestOptionSet?).to(beEmpty())
+        }
+        failsWithErrorMessageForNil("expected to not be empty, got <nil>") {
+            expect(nil as TestOptionSet?).toNot(beEmpty())
+        }
+    }
+}
+
+private struct TestOptionSet: OptionSet, CustomStringConvertible {
+    let rawValue: Int
+
+    static let one = TestOptionSet(rawValue: 1 << 0)
+
+    init(rawValue: Int) {
+        self.rawValue = rawValue
+    }
+
+    var description: String {
+        return "TestOptionSet(rawValue: \(rawValue))"
     }
 }

Tests/NimbleTests/XCTestManifests.swift

@@ -75,6 +75,7 @@ extension BeEmptyTest {
     static let __allTests = [
         ("testBeEmptyNegative", testBeEmptyNegative),
         ("testBeEmptyPositive", testBeEmptyPositive),
+        ("testNilMatches", testNilMatches),
     ]
 }