Improve support for interactive experiences

Expecto.Tests/Bug_RepeatedColourSetting.fs

@@ -0,0 +1,14 @@
+module Bug_RepeatedColourSetting
+
+open Expecto
+open Expecto.Logging
+
+
+[<Tests>]
+let tests =
+  ftest "Colour can be set repeatedly" {
+    let colours = [|Colour0; Colour256|]
+    colours |> Array.iter ANSIOutputWriter.setColourLevel
+
+    Expect.equal (ANSIOutputWriter.getColour ()) (Array.last colours) "Colour should be the last set value"
+  }

Expecto.Tests/Expecto.Tests.fsproj

@@ -13,6 +13,7 @@
     <Compile Include="FsCheckTests.fs" />
     <Compile Include="PerformanceTests.fs" />
     <Compile Include="Bug341.fs" />
+    <Compile Include="Bug_RepeatedColourSetting.fs" />
     <Compile Include="Main.fs" />
     <None Include="paket.references" />
     <ProjectReference Include="..\Expecto.Hopac\Expecto.Hopac.fsproj" />

Expecto/Expecto.fs

@@ -643,3 +643,47 @@ module Tests =
   /// Returns 0 if all tests passed, otherwise 1
   let runTestsInAssemblyWithCLIArgs cliArgs args =
     runTestsInAssemblyWithCLIArgsAndCancel CancellationToken.None cliArgs args
+
+  /// Runs all given tests with the supplied typed command-line options.
+  /// Returns the console output as a string (with ANSI coloring by default)
+  /// Useful for interactive environments like F# interactive or notebooks
+  let runTestsReturnLogs cliArgs args tests =
+    let tryBuildConfig cliArgs args =
+        let config =
+          Seq.fold (fun s a -> foldCLIArgumentToConfig a s)
+            ExpectoConfig.defaultConfig cliArgs
+
+        match ExpectoConfig.fillFromArgs config args with
+        | ArgsUsage (usage, errors) ->
+          None
+        | ArgsList config 
+        | ArgsRun config 
+        | ArgsVersion config ->
+          Some config
+
+    let literateOutputWriter (outputBuilder: Text.StringBuilder) (text: (string*ConsoleColor) list) : unit =
+      let colorizeLine (text, color) = ColourText.colouriseText color text
+      let sbAppend (builder: Text.StringBuilder) (text: string) =
+        builder.Append(text)
+
+      text
+      |> List.iter (colorizeLine >> (sbAppend outputBuilder) >> ignore)
+
+    let outputBuilder = System.Text.StringBuilder("")
+
+    let verbosity = 
+      tryBuildConfig cliArgs args 
+      |> Option.defaultValue ExpectoConfig.defaultConfig 
+      |> (fun config -> config.verbosity)
+
+    Global.initialise 
+      { Global.defaultConfig with
+          getLogger = fun name ->
+            Expecto.Logging.LiterateConsoleTarget(
+              name, 
+              minLevel = verbosity, 
+              outputWriter = (literateOutputWriter outputBuilder)) :> Expecto.Logging.Logger
+      }
+
+    runTestsWithCLIArgs cliArgs args tests |> ignore
+    outputBuilder.ToString()

Expecto/Logging.fs

@@ -879,7 +879,7 @@ module internal ANSIOutputWriter =
     override __.WriteLine() = write "\n"
 
   let mutable internal colours = None
-  let internal setColourLevel c = if colours.IsNone then colours <- Some c
+  let internal setColourLevel c = colours <- Some c
   let internal getColour() = Option.defaultValue Colour8 colours
 
   let colourReset = "\u001b[0m"

README.md

@@ -53,6 +53,7 @@ What follows is the Table of Contents for this README, which also serves as the
   - [`runTestsWithCLIArgsAndCancel`](#runtestswithcliargsandcancel)
   - [`runTestsInAssemblyWithCLIArgs`](#runtestsinassemblywithcliargs)
   - [`runTestsInAssemblyWithCLIArgsAndCancel`](#runtestsinassemblywithcliargsandcancel)
+  - [`runTestsReturnLogs`](#runtestsreturnlogs)
   - [Filtering with `filter`](#filtering-with-filter)
   - [Shuffling with `shuffle`](#shuffling-with-shuffle)
   - [Stress testing](#stress-testing)
@@ -250,6 +251,22 @@ Signature `CancellationToken -> CLIArguments seq -> string[] -> int`. Runs the t
 assembly and also overrides the passed `CLIArguments` with the command line
 parameters. All tests need to be marked with the `[<Tests>]` attribute.
 
+### `runTestsReturnLogs`
+
+Signature `CLIArguments seq -> string[] -> Test -> string`.
+Accepts the same arguments as `runTestsWithCLIArgs`, but returns the console output as a string.
+
+This is useful for interactive environments like [F# interactive](https://learn.microsoft.com/en-us/dotnet/fsharp/tools/fsharp-interactive/) and [Polyglot Notebooks](https://marketplace.visualstudio.com/items?itemName=ms-dotnettools.dotnet-interactive-vscode), where console output is not available but the returned string can be displayed instead.
+
+Note that ANSI colors are used by default, but can be turned off using `--colours 0`.
+```fsharp
+runTestsReturnLogs [] [|"--colours";"0"|] tests
+```
+
+Any valid CLI arguments work, including `--help` and `--list-tests`.
+
+
+
 ### Filtering with `filter`
 
 You can single out tests by filtering them by name (e.g. in the