Merge pull request #25 from Tarmil/exec-newlines

fix(Exec): Preserve newlines except the final one

src/FSharp.Data.LiteralProviders.DesignTime/Exec.fs

@@ -41,6 +41,28 @@ let (|Args|_|) baseDir (args: obj[]) =
         |> Some
     | _ -> None
 
+type OutputLineState =
+    | FirstLine
+    | SubsequentLine of lastLineWasEmpty: bool
+
+/// We want to include all newlines except the final one, if any.
+let readOutput (event: IEvent<DataReceivedEventHandler, DataReceivedEventArgs>) =
+    let output = StringBuilder()
+    event
+    |> Event.filter (fun e -> not (isNull e.Data))
+    |> Event.scan (fun lineState e ->
+        let thisLineIsEmpty = e.Data = ""
+        match lineState with
+        | FirstLine ->
+            output.Append(e.Data) |> ignore
+        | SubsequentLine lastLineWasEmpty when lastLineWasEmpty || not thisLineIsEmpty ->
+            output.AppendLine().Append(e.Data) |> ignore
+        | SubsequentLine _ -> ()
+        SubsequentLine thisLineIsEmpty
+    ) FirstLine
+    |> Event.add ignore
+    output
+
 let execute args =
     let proc = new Process()
     proc.StartInfo.UseShellExecute <- false
@@ -50,10 +72,8 @@ let execute args =
     proc.StartInfo.RedirectStandardInput <- true
     proc.StartInfo.RedirectStandardOutput <- true
     proc.StartInfo.RedirectStandardError <- true
-    let output = StringBuilder()
-    let error = StringBuilder()
-    proc.OutputDataReceived.Add(fun e -> output.Append(e.Data) |> ignore)
-    proc.ErrorDataReceived.Add(fun e -> error.Append(e.Data) |> ignore)
+    let output = readOutput proc.OutputDataReceived
+    let error = readOutput proc.ErrorDataReceived
     proc.Start() |> ignore
     let startTime = try proc.StartTime with _ -> DateTime.Now
     args.Input |> Option.iter proc.StandardInput.Write

tests/FSharp.Data.LiteralProviders.Tests/Exec.fs

@@ -10,8 +10,17 @@ type DotnetListReference = Exec<"dotnet", "list reference">
 let ``with success`` () =
     test <@ DotnetListReference.ExitCode = 0 @>
     test <@ DotnetListReference.Error = "" @>
-    test <@ DotnetListReference.Output.StartsWith("Project reference(s)") @>
-    test <@ DotnetListReference.Output.EndsWith(".fsproj") @>
+    test <@ DotnetListReference.Output =
+                ([ @"Project reference(s)"
+                   @"--------------------"
+                   @"..\..\src\FSharp.Data.LiteralProviders.Runtime\FSharp.Data.LiteralProviders.Runtime.fsproj" ]
+                |> String.concat System.Environment.NewLine) @>
+
+type DotnetVersion = Exec<"dotnet", "--version">
+
+[<Test>]
+let ``single line excludes newline`` () =
+    test <@ not <| DotnetVersion.Output.Contains("\n") @>
 
 type DotnetListError = Exec<"dotnet", "list whatever">