diff --git a/MultiversalDiplomacyTests/ReplDriver.cs b/MultiversalDiplomacyTests/ReplDriver.cs
new file mode 100644
index 0000000..ff3b99f
--- /dev/null
+++ b/MultiversalDiplomacyTests/ReplDriver.cs
@@ -0,0 +1,51 @@
+using NUnit.Framework;
+
+using MultiversalDiplomacy.Script;
+
+namespace MultiversalDiplomacyTests;
+
+public class ReplDriver(IScriptHandler initialHandler, bool echo = false)
+{
+    public IScriptHandler? Handler { get; private set; } = initialHandler;
+
+    private string? LastInput { get; set; } = "";
+
+    /// <summary>
+    /// Whether to print the inputs as they are executed. This is primarily a debugging aid.
+    /// </summary>
+    bool Echo { get; } = echo;
+
+    /// <summary>
+    /// Input a multiline string into the repl. Call <see cref="Ready"/> or <see cref="Closed"/> at the end so the
+    /// statement is valid.
+    /// </summary>
+    public ReplDriver this[string input] => ExecuteAll(input);
+
+    public ReplDriver ExecuteAll(string multiline)
+    {
+        var lines = multiline.Split('\n', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
+        return lines.Aggregate(this, (repl, line) => repl.Execute(line));
+    }
+
+    public ReplDriver Execute(string inputLine)
+    {
+        if (Handler is null) throw new AssertionException(
+            $"Cannot execute \"{inputLine}\", handler quit. Last input was \"{LastInput}\"");
+        if (Echo) Console.WriteLine($"{Handler.Prompt}{inputLine}");
+
+        Handler = Handler.HandleInput(inputLine);
+        LastInput = inputLine;
+
+        return this;
+    }
+
+    public void Ready()
+    {
+        Assert.That(Handler, Is.Not.Null, "Handler is closed");
+    }
+
+    public void Closed()
+    {
+        Assert.That(Handler, Is.Null, "Handler is not closed");
+    }
+}
diff --git a/MultiversalDiplomacyTests/ReplTest.cs b/MultiversalDiplomacyTests/ReplTest.cs
new file mode 100644
index 0000000..2d81caf
--- /dev/null
+++ b/MultiversalDiplomacyTests/ReplTest.cs
@@ -0,0 +1,35 @@
+using NUnit.Framework;
+
+using MultiversalDiplomacy.Model;
+using MultiversalDiplomacy.Script;
+
+namespace MultiversalDiplomacyTests;
+
+public class ReplTest
+{
+    [Test]
+    public void SetupHandler()
+    {
+        SetupScriptHandler setup = new(World.WithStandardMap(), strict: true);
+        ReplDriver repl = new(setup);
+
+        repl["""
+        unit Germany A Munich
+        unit Austria Army Tyrolia
+        unit England F London
+        """].Ready();
+
+        Assert.That(repl.Handler, Is.TypeOf<SetupScriptHandler>());
+        SetupScriptHandler handler = (SetupScriptHandler)repl.Handler!;
+        Assert.That(handler.World.Units.Count, Is.EqualTo(3));
+        Assert.That(handler.World.GetUnitAt("Mun"), Is.Not.Null);
+        Assert.That(handler.World.GetUnitAt("Tyr"), Is.Not.Null);
+        Assert.That(handler.World.GetUnitAt("Lon"), Is.Not.Null);
+
+        repl["""
+        ---
+        """].Ready();
+
+        Assert.That(repl.Handler, Is.TypeOf<GameScriptHandler>());
+    }
+}