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diff --git a/src/main/scala/com/iinteractive/test/ExternalTest.scala b/src/main/scala/com/iinteractive/test/ExternalTest.scala
new file mode 100644
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--- /dev/null
+++ b/src/main/scala/com/iinteractive/test/ExternalTest.scala
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+package com.iinteractive.test
+
+import scala.concurrent.Await
+import scala.concurrent.duration.Duration
+import scala.concurrent.ExecutionContext.Implicits.global
+import scala.concurrent.Future
+import scala.concurrent.Future._
+import scala.annotation.tailrec
+
+/** Runs an external process which emits TAP, and parses it as a test.
+  *
+  * This test class can be used if you have existing tests that you would like
+  * to be able to include in a test suite using this framework. You just need
+  * to write a test class for each external test that looks like this:
+  *
+  * {{{
+  * class MyTest1 extends ExternalTest("perl", "t/basic.t")
+  * }}}
+  *
+  * This will run your external process, and use its TAP stream as its output.
+  * This will allow it to, for instance, be a part of the test suite that runs
+  * via `sbt test`. As with any other test class, its stdout and stderr will
+  * be sent to `Console.out` and `Console.err`, where they can be overridden
+  * as needed.
+  */
+class ExternalTest (cmdLine: String*) extends Test {
+  protected def runTests (raw: Boolean): Int = {
+    val processBuilder = new ProcessBuilder(cmdLine: _*)
+
+    // Ensure that if stdout and stderr are both pointing to the same place (a
+    // terminal or file or something) that they remain synchronized. This is
+    // only possible if the endpoint they are streaming to is the same place
+    // underneath, with no extra processing in between. (This is safe because
+    // stdout is typically line-buffered, and we only ever output a line at a
+    // time when writing TAP, so in theory, buffering of the underlying file
+    // descriptor shouldn't make a difference here)
+    if (Console.out eq System.out) {
+      processBuilder.redirectOutput(ProcessBuilder.Redirect.INHERIT)
+    }
+    if (Console.err eq System.err) {
+      processBuilder.redirectError(ProcessBuilder.Redirect.INHERIT)
+    }
+
+    val process = processBuilder.start
+
+    val streams = Seq(
+      Console.out -> process.getInputStream,
+      Console.err -> process.getErrorStream
+    )
+
+    val listeners = streams.map { case (out, in) =>
+      Future {
+        val buf = new Array[Byte](1024)
+
+        @tailrec
+        def read {
+          val bytes = in.read(buf)
+          if (bytes >= 0) {
+            out.print(new String(buf.take(bytes)))
+            read
+          }
+        }
+
+        read
+        true
+      }
+    }
+
+    val exitCode = process.waitFor
+    Await.ready(Future.sequence(listeners), Duration.Inf)
+    exitCode
+  }
+}