Add workarounds for Swift’s missing Quarter operations (#65)

Author: winsmith

Package.resolved

@@ -18,8 +18,8 @@ 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: "2.0.0"),
+        // .package(name: "SwiftDateOperations", path: "../SwiftDateOperations"), // local development
+        .package(url: "https://github.com/TelemetryDeck/SwiftDateOperations.git", from: "2.0.1"),
         .package(url: "https://github.com/apple/swift-crypto.git", from: "3.8.0"),
     ],
     targets: [

Package.swift

@@ -66,21 +66,77 @@ public struct RelativeDate: Codable, Hashable, Equatable, Sendable {
 }
 
 public extension Date {
-    static func from(relativeDate: RelativeDate) -> Date {
-        var date = Date()
+    static func from(relativeDate: RelativeDate, originDate: Date? = nil) -> Date {
+        var date = originDate ?? Date()
 
         let calendarComponent = relativeDate.component.calendarComponent
-        date = date.calendar.date(byAdding: calendarComponent, value: relativeDate.offset, to: date) ?? date
 
-        switch relativeDate.position {
-        case .beginning:
-            date = date.beginning(of: calendarComponent) ?? date
-        case .end:
-            date = date.end(of: calendarComponent) ?? date
+        // Swift's Calendar has a known bug where adding/subtracting .quarter doesn't work correctly.
+        // Work around this by converting quarters to months (1 quarter = 3 months).
+        if relativeDate.component == .quarter {
+            date = date.calendar.date(byAdding: .month, value: relativeDate.offset * 3, to: date) ?? date
+        } else {
+            date = date.calendar.date(byAdding: calendarComponent, value: relativeDate.offset, to: date) ?? date
+        }
+
+        // Swift's Calendar also has bugs with beginning(of: .quarter) and end(of: .quarter).
+        // Implement custom quarter boundary logic.
+        if relativeDate.component == .quarter {
+            switch relativeDate.position {
+            case .beginning:
+                date = date.beginningOfQuarter ?? date
+            case .end:
+                date = date.endOfQuarter ?? date
+            }
+        } else {
+            switch relativeDate.position {
+            case .beginning:
+                date = date.beginning(of: calendarComponent) ?? date
+            case .end:
+                date = date.end(of: calendarComponent) ?? date
+            }
         }
 
         return date
     }
+
+    /// Returns the first moment of the quarter containing this date.
+    /// Q1: Jan 1, Q2: Apr 1, Q3: Jul 1, Q4: Oct 1
+    private var beginningOfQuarter: Date? {
+        let month = calendar.component(.month, from: self)
+        let year = calendar.component(.year, from: self)
+
+        // Determine the first month of the quarter (1, 4, 7, or 10)
+        let quarterIndex = (month - 1) / 3  // 0, 1, 2, or 3
+        let firstMonthOfQuarter = quarterIndex * 3 + 1
+
+        var components = DateComponents()
+        components.year = year
+        components.month = firstMonthOfQuarter
+        components.day = 1
+        components.hour = 0
+        components.minute = 0
+        components.second = 0
+        components.nanosecond = 0
+
+        return calendar.date(from: components)
+    }
+
+    /// Returns the last moment of the quarter containing this date.
+    /// Q1: Mar 31 23:59:59, Q2: Jun 30, Q3: Sep 30, Q4: Dec 31
+    private var endOfQuarter: Date? {
+        guard let beginningOfNextQuarter = quarterAfter?.beginningOfQuarter else {
+            return nil
+        }
+
+        // Subtract 1 second to get the last moment of the current quarter
+        return calendar.date(byAdding: .second, value: -1, to: beginningOfNextQuarter)
+    }
+
+    /// Returns a date in the next quarter
+    private var quarterAfter: Date? {
+        calendar.date(byAdding: .month, value: 3, to: self)
+    }
 }
 
 public extension QueryTimeInterval {

Sources/DataTransferObjects/Query/RelativeTimeInterval.swift

@@ -157,6 +157,27 @@ final class RelativeDateTests: XCTestCase {
         XCTAssertEqual(in30HoursAbsolute, Date.from(relativeDate: in30HoursRelative))
     }
 
+    func testDateFromRelativeQuarter() throws {
+        // Jan 12, 2026 is in Q1 2026
+        // -1 quarter = -3 months → Oct 12, 2025 (Q4 2025)
+        // Beginning of Q4 2025 = Oct 1, 2025
+        let beginningOfLastQuarterRelative = RelativeDate(.beginning, of: .quarter, adding: -1)
+        let beginningOfLastQuarterAbsolute = Date(iso8601String: "2025-10-01T00:00:00.000Z")!
+
+        XCTAssertEqual(beginningOfLastQuarterAbsolute, Date.from(relativeDate: beginningOfLastQuarterRelative, originDate: Date(iso8601String: "2026-01-12T00:00:00.000Z")!))
+    }
+
+    func testDateFromRelativeQuarterOverYear() throws {
+        // Jan 12, 2026 is in Q1 2026
+        // -2 quarters = -6 months → Jul 12, 2025 (Q3 2025)
+        // Beginning of Q3 2025 = Jul 1, 2025
+        let beginningOfLastQuarterRelative = RelativeDate(.beginning, of: .quarter, adding: -2)
+        let beginningOfLastQuarterAbsolute = Date(iso8601String: "2025-07-01T00:00:00.000Z")!
+
+        XCTAssertEqual(beginningOfLastQuarterAbsolute, Date.from(relativeDate: beginningOfLastQuarterRelative, originDate: Date(iso8601String: "2026-01-12T00:00:00.000Z")!))
+    }
+
+
     func testWeekBeginsOnMonday() throws {
         let beginningOfNextWeekRelative = RelativeDate(.beginning, of: .week, adding: 1)
         let beginningOfNextWeekAbsolute = Date.from(relativeDate: beginningOfNextWeekRelative)
@@ -167,4 +188,107 @@ final class RelativeDateTests: XCTestCase {
 
         XCTAssertEqual("Monday", weekDay)
     }
+
+    // MARK: - Comprehensive Quarter Tests
+
+    func testQuarterEndCalculation() throws {
+        // Jan 12, 2026 is in Q1 2026
+        // End of current quarter (Q1 2026) = Mar 31, 2026 23:59:59
+        let endOfCurrentQuarterRelative = RelativeDate(.end, of: .quarter, adding: 0)
+        let endOfCurrentQuarterAbsolute = Date.from(relativeDate: endOfCurrentQuarterRelative, originDate: Date(iso8601String: "2026-01-12T00:00:00.000Z")!)
+
+        // Use UTC calendar for timezone-safe comparison
+        var calendar = Calendar(identifier: .gregorian)
+        calendar.timeZone = TimeZone(identifier: "UTC")!
+        let components = calendar.dateComponents([.year, .month, .day], from: endOfCurrentQuarterAbsolute)
+        XCTAssertEqual(components.year, 2026)
+        XCTAssertEqual(components.month, 3)
+        XCTAssertEqual(components.day, 31)
+    }
+
+    func testQuarterAddingPositiveOffset() throws {
+        // Jan 12, 2026 is in Q1 2026
+        // +1 quarter = +3 months → Apr 12, 2026 (Q2 2026)
+        // Beginning of Q2 2026 = Apr 1, 2026
+        let beginningOfNextQuarterRelative = RelativeDate(.beginning, of: .quarter, adding: 1)
+        let beginningOfNextQuarterAbsolute = Date(iso8601String: "2026-04-01T00:00:00.000Z")!
+
+        XCTAssertEqual(beginningOfNextQuarterAbsolute, Date.from(relativeDate: beginningOfNextQuarterRelative, originDate: Date(iso8601String: "2026-01-12T00:00:00.000Z")!))
+    }
+
+    func testQuarterAddingMultiplePositiveOffsets() throws {
+        // Jan 12, 2026 is in Q1 2026
+        // +4 quarters = +12 months → Jan 12, 2027 (Q1 2027)
+        // Beginning of Q1 2027 = Jan 1, 2027
+        let beginningOfFourQuartersAheadRelative = RelativeDate(.beginning, of: .quarter, adding: 4)
+        let beginningOfFourQuartersAheadAbsolute = Date(iso8601String: "2027-01-01T00:00:00.000Z")!
+
+        XCTAssertEqual(beginningOfFourQuartersAheadAbsolute, Date.from(relativeDate: beginningOfFourQuartersAheadRelative, originDate: Date(iso8601String: "2026-01-12T00:00:00.000Z")!))
+    }
+
+    func testQuarterCurrentQuarter() throws {
+        // Jan 12, 2026 is in Q1 2026
+        // 0 quarters offset = stay in Q1 2026
+        // Beginning of Q1 2026 = Jan 1, 2026
+        let beginningOfCurrentQuarterRelative = RelativeDate(.beginning, of: .quarter, adding: 0)
+        let beginningOfCurrentQuarterAbsolute = Date(iso8601String: "2026-01-01T00:00:00.000Z")!
+
+        XCTAssertEqual(beginningOfCurrentQuarterAbsolute, Date.from(relativeDate: beginningOfCurrentQuarterRelative, originDate: Date(iso8601String: "2026-01-12T00:00:00.000Z")!))
+    }
+
+    func testQuarterFromMiddleOfQuarter() throws {
+        // May 15, 2026 is in Q2 2026
+        // -1 quarter = -3 months → Feb 15, 2026 (Q1 2026)
+        // Beginning of Q1 2026 = Jan 1, 2026
+        let beginningOfPreviousQuarterRelative = RelativeDate(.beginning, of: .quarter, adding: -1)
+        let beginningOfPreviousQuarterAbsolute = Date(iso8601String: "2026-01-01T00:00:00.000Z")!
+
+        XCTAssertEqual(beginningOfPreviousQuarterAbsolute, Date.from(relativeDate: beginningOfPreviousQuarterRelative, originDate: Date(iso8601String: "2026-05-15T00:00:00.000Z")!))
+    }
+
+    func testQuarterFromEndOfQuarter() throws {
+        // Mar 31, 2026 is in Q1 2026
+        // -1 quarter = -3 months → Dec 31, 2025 (Q4 2025)
+        // Beginning of Q4 2025 = Oct 1, 2025
+        let beginningOfPreviousQuarterRelative = RelativeDate(.beginning, of: .quarter, adding: -1)
+        let beginningOfPreviousQuarterAbsolute = Date(iso8601String: "2025-10-01T00:00:00.000Z")!
+
+        XCTAssertEqual(beginningOfPreviousQuarterAbsolute, Date.from(relativeDate: beginningOfPreviousQuarterRelative, originDate: Date(iso8601String: "2026-03-31T00:00:00.000Z")!))
+    }
+
+    func testQuarterCrossingMultipleYears() throws {
+        // Jan 12, 2026 is in Q1 2026
+        // -5 quarters = -15 months → Oct 12, 2024 (Q4 2024)
+        // Beginning of Q4 2024 = Oct 1, 2024
+        let beginningOfFiveQuartersBackRelative = RelativeDate(.beginning, of: .quarter, adding: -5)
+        let beginningOfFiveQuartersBackAbsolute = Date(iso8601String: "2024-10-01T00:00:00.000Z")!
+
+        XCTAssertEqual(beginningOfFiveQuartersBackAbsolute, Date.from(relativeDate: beginningOfFiveQuartersBackRelative, originDate: Date(iso8601String: "2026-01-12T00:00:00.000Z")!))
+    }
+
+    func testQuarterEndCrossingYear() throws {
+        // Jan 12, 2026 is in Q1 2026
+        // -1 quarter = -3 months → Oct 12, 2025 (Q4 2025)
+        // End of Q4 2025 = Dec 31, 2025 23:59:59
+        let endOfPreviousQuarterRelative = RelativeDate(.end, of: .quarter, adding: -1)
+        let endOfPreviousQuarterAbsolute = Date.from(relativeDate: endOfPreviousQuarterRelative, originDate: Date(iso8601String: "2026-01-12T00:00:00.000Z")!)
+
+        // Use UTC calendar for timezone-safe comparison
+        var calendar = Calendar(identifier: .gregorian)
+        calendar.timeZone = TimeZone(identifier: "UTC")!
+        let components = calendar.dateComponents([.year, .month, .day], from: endOfPreviousQuarterAbsolute)
+        XCTAssertEqual(components.year, 2025)
+        XCTAssertEqual(components.month, 12)
+        XCTAssertEqual(components.day, 31)
+    }
+
+    func testQuarterFromQ3() throws {
+        // Aug 15, 2025 is in Q3 2025
+        // -2 quarters = -6 months → Feb 15, 2025 (Q1 2025)
+        // Beginning of Q1 2025 = Jan 1, 2025
+        let beginningOfTwoQuartersBackRelative = RelativeDate(.beginning, of: .quarter, adding: -2)
+        let beginningOfTwoQuartersBackAbsolute = Date(iso8601String: "2025-01-01T00:00:00.000Z")!
+
+        XCTAssertEqual(beginningOfTwoQuartersBackAbsolute, Date.from(relativeDate: beginningOfTwoQuartersBackRelative, originDate: Date(iso8601String: "2025-08-15T00:00:00.000Z")!))
+    }
 }