Change DateFormat to use the full ISO8601 date format by default

Sources/TemplateKit/Tag/DateFormat.swift

@@ -4,8 +4,39 @@
 ///
 /// If no date format is supplied, a default will be used.
 public final class DateFormat: TagRenderer {
+    public typealias DateFormatterFactory = () -> DateFormatter
+
+    private let defaultDateFormatterFactory: DateFormatterFactory
+
+    private static let dateAndTimeFormatterFactory: DateFormatterFactory = {
+        let dateFormatter = DateFormatter()
+        dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
+        return dateFormatter
+    }
+
+    private static let iso8601FormatterFactory: DateFormatterFactory = {
+        let dateFormatter = DateFormatter()
+        dateFormatter.calendar = Calendar(identifier: .iso8601)
+        dateFormatter.locale = Locale(identifier: "en_US_POSIX")
+        dateFormatter.timeZone = TimeZone(secondsFromGMT: 0)
+        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSXXXXX"
+        return dateFormatter
+    }
+
+    /// Creates a new `DateFormat` tag renderer.
+    public convenience init() {
+        self.init(defaultDateFormatterFactory: DateFormat.dateAndTimeFormatterFactory)
+    }
+
     /// Creates a new `DateFormat` tag renderer.
-    public init() {}
+    /// - parameter defaultDateFormatter: The date formatter to use when the tag invocation
+    ///   does not specify a date format.
+    public init(defaultDateFormatterFactory: @escaping DateFormatterFactory) {
+        self.defaultDateFormatterFactory = defaultDateFormatterFactory
+    }
+
+    /// A `DateFormat` tag renderer that uses ISO 8601 date formatting by default.
+    public static let iso8601 = DateFormat(defaultDateFormatterFactory: DateFormat.iso8601FormatterFactory)
 
     /// See `TagRenderer`.
     public func render(tag: TagContext) throws -> Future<TemplateData> {
@@ -28,21 +59,24 @@ public final class DateFormat: TagRenderer {
             tag.context.userInfo[DateFormatterCache.userInfoKey] = dateFormatterCache
         }
 
-        let dateFormat: String
-        /// Set format as the second param or default to ISO-8601 format.
-        if tag.parameters.count == 2, let param = tag.parameters[1].string {
-            dateFormat = param
-        } else {
-            dateFormat = "yyyy-MM-dd HH:mm:ss"
+        let dateFormatter: DateFormatter
+        var dateFormat: String?
+        if tag.parameters.count == 2 {
+            /// Set format as the second param. If that's not available, we'll use `self.defaultDateFormatterFactory`.
+            dateFormat = tag.parameters[1].string
         }
 
-        let dateFormatter: DateFormatter
-        if let formatter = dateFormatterCache.dateFormatters[dateFormat] {
+        let cacheKey = dateFormat ?? DateFormatterCache.defaultFormatterPlaceholderKey
+        if let formatter = dateFormatterCache.dateFormatters[cacheKey] {
             dateFormatter = formatter
         } else {
-            dateFormatter = DateFormatter()
-            dateFormatter.dateFormat = dateFormat
-            dateFormatterCache.dateFormatters[dateFormat] = dateFormatter
+            if let dateFormat = dateFormat {
+                dateFormatter = DateFormatter()
+                dateFormatter.dateFormat = dateFormat
+            } else {
+                dateFormatter = self.defaultDateFormatterFactory()
+            }
+            dateFormatterCache.dateFormatters[cacheKey] = dateFormatter
         }
 
         /// Return formatted date
@@ -52,6 +86,7 @@ public final class DateFormat: TagRenderer {
 
 private class DateFormatterCache {
     static let userInfoKey = "TemplateKit.DateFormatterCache"
+    static let defaultFormatterPlaceholderKey = "DEFAULT"
 
     var dateFormatters: [String: DateFormatter] = [:]
 }

Tests/TemplateKitTests/TemplateDataEncoderTests.swift

@@ -261,8 +261,7 @@ class TemplateDataEncoderTests: XCTestCase {
         let user = User(id: nil, name: "Vapor")
         let profile = Profile(currentUser: Future.map(on: worker) { user })
 
-        let data = try TemplateDataEncoder().testEncode(profile, on: worker)
-        print(data)
+        let data = try TemplateDataEncoder().testEncode(profile)
         let container = BasicContainer(config: .init(), environment: .testing, services: .init(), on: worker)
 
         let renderer = PlaintextRenderer(viewsDir: "/", on: container)
@@ -276,20 +275,20 @@ class TemplateDataEncoderTests: XCTestCase {
         XCTAssertEqual(String(data: view.data, encoding: .utf8), "headVaportail")
     }
 
-    // https://github.com/vapor/template-kit/issues/20
-    func testGH20() throws {
+    private func checkDateFormatting(
+        dateFormat: DateFormat, dateFormatter: DateFormatter, file: StaticString = #file, line: UInt = #line) throws {
         func wrap(_ syntax: TemplateSyntaxType) -> TemplateSyntax {
             return TemplateSyntax(type: syntax, source: TemplateSource(file: "test", line: 0, column: 0, range: 0..<1))
         }
-        
+
         let path: [CodingKey] = [
             BasicKey.init("date"),
         ]
 
         let worker = EmbeddedEventLoop()
         let container = BasicContainer(config: .init(), environment: .testing, services: .init(), on: worker)
         let renderer = PlaintextRenderer(viewsDir: "/", on: container)
-        renderer.tags["date"] = DateFormat()
+        renderer.tags["date"] = dateFormat
         let ast: [TemplateSyntax] = [
             wrap(.tag(TemplateTag(
                 name: "date",
@@ -299,16 +298,51 @@ class TemplateDataEncoderTests: XCTestCase {
         ]
         let date = Date()
         let data = try TemplateDataEncoder().testEncode(["date": date])
-        print(data)
         let view = try TemplateSerializer(
             renderer: renderer,
             context: TemplateDataContext(data: data),
             using: container
         ).serialize(ast: ast).wait()
-        let formatter = DateFormatter()
-        formatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
-        print(formatter.string(from: date))
-        XCTAssertEqual(String(data: view.data, encoding: .utf8), formatter.string(from: date))
+        XCTAssertEqual(String(data: view.data, encoding: .utf8), dateFormatter.string(from: date), file: file, line: line)
+    }
+
+    // https://github.com/vapor/template-kit/issues/20
+    func testGH20() throws {
+        let dateFormatter = DateFormatter()
+        dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
+        try checkDateFormatting(dateFormat: DateFormat(), dateFormatter: dateFormatter)
+    }
+
+    func testISO8601DateFormat() throws {
+        let dateFormatter = DateFormatter()
+        dateFormatter.calendar = Calendar(identifier: .iso8601)
+        dateFormatter.locale = Locale(identifier: "en_US_POSIX")
+        dateFormatter.timeZone = TimeZone(secondsFromGMT: 0)
+        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSXXXXX"
+        try checkDateFormatting(dateFormat: .iso8601, dateFormatter: dateFormatter)
+    }
+
+    func testDateFormatterThreadSafety() throws {
+        let dateFormatter = DateFormatter()
+        dateFormatter.calendar = Calendar(identifier: .iso8601)
+        dateFormatter.locale = Locale(identifier: "en_US_POSIX")
+        dateFormatter.timeZone = TimeZone(secondsFromGMT: 0)
+        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSXXXXX"
+
+        let date = Date()
+        let expectedString = dateFormatter.string(from: date)
+        let queue = OperationQueue()
+        queue.maxConcurrentOperationCount = 8
+        queue.isSuspended = true
+
+        for _ in 0..<50_000 {
+            queue.addOperation {
+                XCTAssertEqual(dateFormatter.string(from: date), expectedString)
+            }
+        }
+
+        queue.isSuspended = false
+        queue.waitUntilAllOperationsAreFinished()
     }
 
     func testTemplabeByteScannerPeak() {

Tests/TemplateKitTests/XCTestManifests.swift

@@ -24,6 +24,7 @@ extension TemplateDataEncoderTests {
     static let __allTests__TemplateDataEncoderTests = [
         ("testArray", testArray),
         ("testComplexEncodable", testComplexEncodable),
+        ("testDateFormatterThreadSafety", testDateFormatterThreadSafety),
         ("testDictionary", testDictionary),
         ("testDouble", testDouble),
         ("testEncodable", testEncodable),
@@ -35,6 +36,7 @@ extension TemplateDataEncoderTests {
         ("testEncodingPerformanceExampleModelJSONBaseline", testEncodingPerformanceExampleModelJSONBaseline),
         ("testGH10", testGH10),
         ("testGH20", testGH20),
+        ("testISO8601DateFormat", testISO8601DateFormat),
         ("testNestedArray", testNestedArray),
         ("testNestedDictionary", testNestedDictionary),
         ("testNestedEncodable", testNestedEncodable),