Cosmos: Add t:DateTimeOffset to unfolds

CHANGELOG.md

@@ -13,17 +13,18 @@ The `Unreleased` section name is replaced by the expected version of next releas
 - `eqx dump` perf + logging improvements
 - `eqx dump -P` turns off JSON pretty printing
 - `Cosmos`: `Tip 200` now logs received `n` and `_etag` values
+- `Cosmos`: Unfolds now write and return `t` (creation `DateTimeOffset.UtcNow`)
 - `EventStore`: Add missing optional parameters for `Connector`: `gossipTimeout` and `clientConnectionTimeout` [#186](https://github.com/jet/equinox/pull/186) :pray: [@AndrewRublyov](https://github.com/AndrewRublyov)
 
 ### Changed
 
+- `SqlStreamStore`.*: Target `SqlStreamStore` v `1.2.0-beta.8`
+- Target `FsCodec` v `2.0.0-rc1`
 - Target `Microsoft.SourceLink.GitHub`, `Microsoft.NETFramework.ReferenceAssemblies` v `1.0.0`
 - Samples etc target `Argu` v `6.0.0`
 - `eqx dump`'s `-J` switch now turns off JSON rendering
 - `eqx -C dump` now renders Store `.Information` logs
 - Samples consistently use `module Fold`, `(Events.ForX streamId)`, removed `(|Stream|)` [#174](https://github.com/jet/equinox/pull/174)
-- Target `FsCodec` v `2.0.0-rc1`
-- `SqlStreamStore`.*: Target `SqlStreamStore` v `1.2.0-beta.8`
 
 ### Removed
 

src/Equinox.Cosmos/Cosmos.fs

@@ -81,6 +81,9 @@ type Unfold =
     {   /// Base: Stream Position (Version) of State from which this Unfold Event was generated
         i: int64
 
+        /// Generation datetime
+        t: DateTimeOffset // ISO 8601 // Not written by versions <= 2.0.0-rc9
+
         /// The Case (Event Type) of this compaction/snapshot, used to drive deserialization
         c: string // required
 
@@ -199,7 +202,7 @@ type internal Enum() =
         Enum.Events(b.i, b.e, startPos, direction)
         |> if direction = Direction.Backward then System.Linq.Enumerable.Reverse else id
     static member Unfolds(xs: Unfold[]) : ITimelineEvent<byte[]> seq = seq {
-        for x in xs -> FsCodec.Core.TimelineEvent.Create(x.i, x.c, x.d, x.m, null, null, DateTimeOffset.MinValue, isUnfold=true) }
+        for x in xs -> FsCodec.Core.TimelineEvent.Create(x.i, x.c, x.d, x.m, null, null, x.t, isUnfold=true) }
     static member EventsAndUnfolds(x: Tip): ITimelineEvent<byte[]> seq =
         Enum.Events x
         |> Seq.append (Enum.Unfolds x.u)
@@ -503,7 +506,7 @@ function sync(req, expIndex, expEtag) {
             e = [| for e in events -> { t = e.Timestamp; c = e.EventType; d = e.Data; m = e.Meta; correlationId = e.CorrelationId; causationId = e.CausationId } |]
             u = Array.ofSeq unfolds }
     let mkUnfold baseIndex (unfolds: IEventData<_> seq) : Unfold seq =
-        unfolds |> Seq.mapi (fun offset x -> { i = baseIndex + int64 offset; c = x.EventType; d = x.Data; m = x.Meta } : Unfold)
+        unfolds |> Seq.mapi (fun offset x -> { i = baseIndex + int64 offset; c = x.EventType; d = x.Data; m = x.Meta; t = DateTimeOffset.UtcNow } : Unfold)
 
     module Initialization =
         open System.Linq

tests/Equinox.Cosmos.Integration/JsonConverterTests.fs

@@ -25,7 +25,8 @@ type Base64ZipUtf8Tests() =
             {   i = 42L
                 c = encoded.EventType
                 d = encoded.Data
-                m = null }
+                m = null
+                t = DateTimeOffset.MinValue }
         let res = JsonConvert.SerializeObject e
         test <@ res.Contains("\"d\":\"") && res.Length < 100 @>
 
@@ -42,7 +43,8 @@ type Base64ZipUtf8Tests() =
             {   i = 42L
                 c = encoded.EventType
                 d = encoded.Data
-                m = null }
+                m = null
+                t = DateTimeOffset.MinValue }
         let ser = JsonConvert.SerializeObject(e)
         test <@ ser.Contains("\"d\":\"") @>
         let des = JsonConvert.DeserializeObject<Store.Unfold>(ser)