Add a initializer to Google_Protobuf_Duration with rounding control. (#1747)

Provide a new initializer with explicit rounding controls and map the
other initializer though the single code paths.

Author: thomasvl

Sources/SwiftProtobuf/Google_Protobuf_Duration+Extensions.swift

@@ -144,10 +144,7 @@ extension Google_Protobuf_Duration: ExpressibleByFloatLiteral {
     /// that is interpreted as a duration in seconds, rounded to the nearest
     /// nanosecond.
     public init(floatLiteral value: Double) {
-        let sd = trunc(value)
-        let nd = round((value - sd) * TimeInterval(nanosPerSecond))
-        let (s, n) = normalizeForDuration(seconds: Int64(sd), nanos: Int32(nd))
-        self.init(seconds: s, nanos: n)
+        self.init(rounding: value, rule: .toNearestOrAwayFromZero)
     }
 }
 
@@ -156,10 +153,25 @@ extension Google_Protobuf_Duration {
     /// `TimeInterval` (measured in seconds), rounded to the nearest nanosecond.
     ///
     /// - Parameter timeInterval: The `TimeInterval`.
+    @available(*, deprecated, renamed: "init(rounding:rule:)")
     public init(timeInterval: TimeInterval) {
-        let sd = trunc(timeInterval)
-        let nd = round((timeInterval - sd) * TimeInterval(nanosPerSecond))
-        let (s, n) = normalizeForDuration(seconds: Int64(sd), nanos: Int32(nd))
+        self.init(rounding: timeInterval, rule: .toNearestOrAwayFromZero)
+    }
+
+    /// Creates a new `Google_Protobuf_Duration` that is equal to the given
+    /// `TimeInterval` (measured in seconds), rounded to the nearest nanosecond
+    /// according to the given rounding rule.
+    ///
+    /// - Parameters:
+    ///   - timeInterval: The `TimeInterval`.
+    ///   - rule: The rounding rule to use.
+    public init(
+        rounding timeInterval: TimeInterval,
+        rule: FloatingPointRoundingRule = .toNearestOrAwayFromZero
+    ) {
+        let sd = Int64(timeInterval)
+        let nd = ((timeInterval - Double(sd)) * TimeInterval(nanosPerSecond)).rounded(rule)
+        let (s, n) = normalizeForDuration(seconds: sd, nanos: Int32(nd))
         self.init(seconds: s, nanos: n)
     }
 

Tests/SwiftProtobufTests/Test_Duration.swift

@@ -259,50 +259,74 @@ final class Test_Duration: XCTestCase, PBTestHelpers {
         XCTAssertEqual("{\"optionalDuration\":\"100.000000001s\"}", try c.jsonString())
     }
 
-    func testInitializationByTimeIntervals() throws {
+    func testInitializationRoundingTimeIntervals() throws {
         // Negative interval
-        let t1 = Google_Protobuf_Duration(timeInterval: -123.456)
+        let t1 = Google_Protobuf_Duration(rounding: -123.456)
         XCTAssertEqual(t1.seconds, -123)
         XCTAssertEqual(t1.nanos, -456_000_000)
 
         // Full precision
-        let t2 = Google_Protobuf_Duration(timeInterval: -123.999999999)
+        let t2 = Google_Protobuf_Duration(rounding: -123.999999999)
         XCTAssertEqual(t2.seconds, -123)
         XCTAssertEqual(t2.nanos, -999_999_999)
 
-        // Round up
-        let t3 = Google_Protobuf_Duration(timeInterval: -123.9999999994)
+        // Value past percision, default and some explicit rules
+        let t3 = Google_Protobuf_Duration(rounding: -123.9999999994)
         XCTAssertEqual(t3.seconds, -123)
         XCTAssertEqual(t3.nanos, -999_999_999)
-
-        // Round down
-        let t4 = Google_Protobuf_Duration(timeInterval: -123.9999999996)
+        let t3u = Google_Protobuf_Duration(rounding: -123.9999999994, rule: .up)
+        XCTAssertEqual(t3u.seconds, -123)
+        XCTAssertEqual(t3u.nanos, -999_999_999)
+        let t3d = Google_Protobuf_Duration(rounding: -123.9999999994, rule: .down)
+        XCTAssertEqual(t3d.seconds, -124)
+        XCTAssertEqual(t3d.nanos, 0)
+
+        // Value past percision, default and some explicit rules
+        let t4 = Google_Protobuf_Duration(rounding: -123.9999999996)
         XCTAssertEqual(t4.seconds, -124)
         XCTAssertEqual(t4.nanos, 0)
-
-        let t5 = Google_Protobuf_Duration(timeInterval: 0)
+        let t4u = Google_Protobuf_Duration(rounding: -123.9999999996, rule: .up)
+        XCTAssertEqual(t4u.seconds, -123)
+        XCTAssertEqual(t4u.nanos, -999_999_999)
+        let t4d = Google_Protobuf_Duration(rounding: -123.9999999996, rule: .down)
+        XCTAssertEqual(t4d.seconds, -124)
+        XCTAssertEqual(t4d.nanos, 0)
+
+        let t5 = Google_Protobuf_Duration(rounding: 0)
         XCTAssertEqual(t5.seconds, 0)
         XCTAssertEqual(t5.nanos, 0)
 
         // Positive interval
-        let t6 = Google_Protobuf_Duration(timeInterval: 123.456)
+        let t6 = Google_Protobuf_Duration(rounding: 123.456)
         XCTAssertEqual(t6.seconds, 123)
         XCTAssertEqual(t6.nanos, 456_000_000)
 
         // Full precision
-        let t7 = Google_Protobuf_Duration(timeInterval: 123.999999999)
+        let t7 = Google_Protobuf_Duration(rounding: 123.999999999)
         XCTAssertEqual(t7.seconds, 123)
         XCTAssertEqual(t7.nanos, 999_999_999)
 
-        // Round down
-        let t8 = Google_Protobuf_Duration(timeInterval: 123.9999999994)
+        // Value past percision, default and some explicit rules
+        let t8 = Google_Protobuf_Duration(rounding: 123.9999999994)
         XCTAssertEqual(t8.seconds, 123)
         XCTAssertEqual(t8.nanos, 999_999_999)
-
-        // Round up
-        let t9 = Google_Protobuf_Duration(timeInterval: 123.9999999996)
+        let t8u = Google_Protobuf_Duration(rounding: 123.9999999994, rule: .up)
+        XCTAssertEqual(t8u.seconds, 124)
+        XCTAssertEqual(t8u.nanos, 0)
+        let t8d = Google_Protobuf_Duration(rounding: 123.9999999994, rule: .down)
+        XCTAssertEqual(t8d.seconds, 123)
+        XCTAssertEqual(t8d.nanos, 999_999_999)
+
+        // Value past percision, default and some explicit rules
+        let t9 = Google_Protobuf_Duration(rounding: 123.9999999996)
         XCTAssertEqual(t9.seconds, 124)
         XCTAssertEqual(t9.nanos, 0)
+        let t9u = Google_Protobuf_Duration(rounding: 123.9999999996, rule: .up)
+        XCTAssertEqual(t9u.seconds, 124)
+        XCTAssertEqual(t9u.nanos, 0)
+        let t9d = Google_Protobuf_Duration(rounding: 123.9999999996, rule: .down)
+        XCTAssertEqual(t9d.seconds, 123)
+        XCTAssertEqual(t9d.nanos, 999_999_999)
     }
 
     func testGetters() throws {