The TesterDriverSpec has been made stronger by altering circuit in finish method

1 files changed, 34 insertions, 22 deletions

diff --git a/src/test/scala/chiselTests/TesterDriverSpec.scala b/src/test/scala/chiselTests/TesterDriverSpec.scala
index bfe8602a..d7cb0305 100644
--- a/src/test/scala/chiselTests/TesterDriverSpec.scala
+++ b/src/test/scala/chiselTests/TesterDriverSpec.scala
@@ -5,40 +5,52 @@ package chiselTests
 import Chisel._
 import Chisel.testers.BasicTester
 
-/** Extends basic tester with a finish method.
-  *
+/** Extend basic tester with a finish method.  TesterDriver will call the
+  * finish method after the Tester's constructor has completed
+  * -
+  * In this example we use last connect semantics to alter the circuit after
+  * the constructor has completed
   */
 class FinishTester extends BasicTester {
-  var finish_was_run = false
+  val test_wire_width = 2
+  val test_wire_override_value = 3
+
+  val test_wire = Wire(UInt(1, width = test_wire_width))
+
+  test_wire := UInt(1, width = test_wire_width)
+  // though we just test_wire to 1, the assert below will be true because
+  // the finish will override it
+  assert(test_wire === UInt(test_wire_override_value))
 
   override def finish(): Unit = {
-     finish_was_run = true
+    test_wire := UInt(test_wire_override_value, width = test_wire_width)
   }
 }
 
-class TesterDriverSpec extends ChiselFlatSpec {
-  class DummyCircuit extends Module {
-    val io = new Bundle {
-      val in = UInt(INPUT, width = 1)
-      val out = UInt(OUTPUT, width = 1)
-    }
-
-    io.out := io.in
+class DummyCircuit extends Module {
+  val io = new Bundle {
+    val in = UInt(INPUT, width = 1)
+    val out = UInt(OUTPUT, width = 1)
   }
 
-  class DummyTester extends FinishTester {
-    val dut = new DummyCircuit
+  io.out := io.in
+}
+
+class DummyTester extends FinishTester {
+  val dut = Module(new DummyCircuit)
 
-    dut.io.in := UInt(1)
-    Chisel.assert(dut.io.out === UInt(1))
+  dut.io.in := UInt(1)
+  Chisel.assert(dut.io.out === UInt(1))
 
-    "Extending BasicTester" should "allow developer to have finish method run automatically" in {
-      assert(finish_was_run)
-    }
-  }
+  stop()
+}
 
-  runTester {
-    new DummyTester
+class TesterDriverSpec extends ChiselFlatSpec {
+  "TesterDriver calls a BasicTester subclass's finish method which" should
+    "allow modifications of test circuit after tester constructor is done" in {
+    assertTesterPasses {
+      new DummyTester
+    }
   }
 }