Update DateOperations to use ISO8601 calendar (#47)

Author: winsmith

Package.resolved

@@ -1,4 +1,4 @@
-// swift-tools-version:5.3
+// swift-tools-version:5.5
 // The swift-tools-version declares the minimum version of Swift required to build this package.
 
 import PackageDescription
@@ -19,7 +19,7 @@ let package = Package(
     dependencies: [
         // Dependencies declare other packages that this package depends on.
         // .package(url: /* package url */, from: "1.0.0"),
-        .package(url: "https://github.com/TelemetryDeck/SwiftDateOperations.git", from: "1.0.3"),
+        .package(url: "https://github.com/TelemetryDeck/SwiftDateOperations.git", from: "1.0.4"),
         .package(url: "https://github.com/apple/swift-crypto.git", "1.0.0" ..< "3.0.0"),
     ],
     targets: [

Package.swift

@@ -156,4 +156,15 @@ final class RelativeDateTests: XCTestCase {
 
         XCTAssertEqual(in30HoursAbsolute, Date.from(relativeDate: in30HoursRelative))
     }
+
+    func testWeekBeginsOnMonday() throws {
+        let beginningOfNextWeekRelative = RelativeDate(.beginning, of: .week, adding: 1)
+        let beginningOfNextWeekAbsolute = Date.from(relativeDate: beginningOfNextWeekRelative)
+
+        let dateFormatter = DateFormatter()
+        dateFormatter.dateFormat = "EEEE"
+        let weekDay = dateFormatter.string(from: beginningOfNextWeekAbsolute)
+
+        XCTAssertEqual("Monday", weekDay)
+    }
 }