Add tests for remainder(dividingBy: -1).

Author: stephentyrone

Tests/IntegerUtilitiesTests/DivideTests.swift

@@ -343,4 +343,12 @@ final class IntegerUtilitiesDivideTests: XCTestCase {
     }
     XCTAssertLessThanOrEqual(fails, 32*16)
   }
+  
+  func testRemainderByMinusOne() {
+    // These would trap if implemented as a - bq or similar, even though
+    // the remainder is well-defined.
+    XCTAssertEqual(0, Int.min.remainder(dividingBy: -1))
+    XCTAssertEqual(0, Int.min.remainder(dividingBy: -1, rounding: .up))
+    XCTAssertEqual(0, Int.min.remainder(dividingBy: -1, rounding: .stochastically))
+  }
 }

Tests/WindowsMain.swift

@@ -85,11 +85,12 @@ extension PropertyTests {
 
 extension IntegerUtilitiesDivideTests {
   static var all = testCase([
-    ("testDivideInt8", IntegerUtilitiesDivideTests.testDivideInt8()),
-    ("testDivideInt", IntegerUtilitiesDivideTests.testDivideInt()),
-    ("testDivideUInt8", IntegerUtilitiesDivideTests.testDivideUInt8()),
-    ("testDivideStochasticInt8", IntegerUtilitiesDivideTests.testDivideStochasticInt8()),
-    ("testDivideStochasticUInt32", IntegerUtilitiesDivideTests.testDivideStochasticUInt32()),
+    ("testDivideInt8", IntegerUtilitiesDivideTests.testDivideInt8),
+    ("testDivideInt", IntegerUtilitiesDivideTests.testDivideInt),
+    ("testDivideUInt8", IntegerUtilitiesDivideTests.testDivideUInt8),
+    ("testDivideStochasticInt8", IntegerUtilitiesDivideTests.testDivideStochasticInt8),
+    ("testDivideStochasticUInt32", IntegerUtilitiesDivideTests.testDivideStochasticUInt32),
+    ("testRemainderByMinusOne", IntegerUtilitiesDivideTests.testRemainderByMinusOne),
   ])
 }