This adds a mechanism for the unittests to be run with the TreadleBackend

This mechanism is not enabled and should not change the behavior of existing tests
A following PR will deliver a switch that will allow changing the backend.
The reasons for this PR
- Treadle tests run much faster, enabling quicker debugging and CI cycles
- This will help ensure fidelity of Treadle to the Verilator backend

A few tests are marked as verilator only due to black box limitations

Change treadle to a direct dependency

I tried to make it a test only dependency but the TesterDriver sits in src/main requiring that
regular compile have access to treadle

Oops, made treadle the default

A number of changes in response to @ducky64 review
- made backend check clearer and add error handling for multiple backends specified
- Fixed duplicate TargetDirAnnotation uses in Treadle backend
- Cleaned up BlackBox test formatting
- Undid unnecessary debugging changes from Counter
- Undid .gitignore change, that should be on another PR

A number of changes in response to @ducky64 review
- Undid debugging changes made to BitWiseOps

1 files changed, 11 insertions, 3 deletions

diff --git a/src/test/scala/chiselTests/AnalogIntegrationSpec.scala b/src/test/scala/chiselTests/AnalogIntegrationSpec.scala
index a3e6e643..d28c0ee1 100644
--- a/src/test/scala/chiselTests/AnalogIntegrationSpec.scala
+++ b/src/test/scala/chiselTests/AnalogIntegrationSpec.scala
@@ -4,7 +4,7 @@ package chiselTests
 
 import chisel3._
 import chisel3.util._
-import chisel3.testers.BasicTester
+import chisel3.testers.{BasicTester, TesterDriver}
 import chisel3.experimental._
 
 /* This test is different from AnalogSpec in that it uses more complicated black boxes that can each
@@ -126,10 +126,18 @@ class AnalogIntegrationTester(mod: => AnalogDUTModule) extends BasicTester {
 class AnalogIntegrationSpec extends ChiselFlatSpec {
   behavior of "Verilator"
   it should "support simple bidirectional wires" in {
-    assertTesterPasses(new AnalogIntegrationTester(new AnalogSmallDUT), Seq("/chisel3/AnalogBlackBox.v"))
+    assertTesterPasses(
+      new AnalogIntegrationTester(new AnalogSmallDUT),
+      Seq("/chisel3/AnalogBlackBox.v"),
+      TesterDriver.verilatorOnly
+    )
   }
   // Use this test once Verilator supports alias
   ignore should "support arbitrary bidirectional wires" in {
-    assertTesterPasses(new AnalogIntegrationTester(new AnalogDUT), Seq("/chisel3/AnalogBlackBox.v"))
+    assertTesterPasses(
+      new AnalogIntegrationTester(new AnalogDUT),
+      Seq("/chisel3/AnalogBlackBox.v"),
+      TesterDriver.verilatorOnly
+    )
   }
 }