test: add some baseline BlackBoxGenerator tests.

src/test/scala/ee/hrzn/chryse/platform/cxxrtl/BlackBoxGeneratorSpec.scala

@@ -0,0 +1,62 @@
+package ee.hrzn.chryse.platform.cxxrtl
+
+import chisel3._
+import org.scalatest.flatspec.AnyFlatSpec
+import org.scalatest.matchers.should._
+
+import java.io.StringWriter
+
+class BlackBoxGeneratorSpec extends AnyFlatSpec with Matchers {
+  behavior.of("BlackBoxGenerator")
+
+  it should "generate unary input and output wires correctly" in {
+    val sw = new StringWriter
+    BlackBoxGenerator(sw, classOf[UnaryBB])
+    sw.toString() should be("""attribute \cxxrtl_blackbox 1
+                              |attribute \blackbox 1
+                              |module \UnaryBB
+                              |  attribute \cxxrtl_edge "p"
+                              |  wire input 1 \clock
+                              |
+                              |  wire input 2 \ready
+                              |
+                              |  attribute \cxxrtl_sync 1
+                              |  wire output 3 \valid
+                              |end
+""".stripMargin)
+  }
+
+  it should "expand Vec of Bool correctly" in {
+    val sw = new StringWriter
+    BlackBoxGenerator(sw, classOf[VecOfBoolBB])
+    sw.toString() should be("""attribute \cxxrtl_blackbox 1
+                              |attribute \blackbox 1
+                              |module \VecOfBoolBB
+                              |  wire input 1 \d_in_0
+                              |  wire input 2 \d_in_1
+                              |  wire input 3 \d_in_2
+                              |
+                              |  attribute \cxxrtl_sync 1
+                              |  wire output 4 \d_out_0
+                              |  attribute \cxxrtl_sync 1
+                              |  wire output 5 \d_out_1
+                              |end
+""".stripMargin)
+  }
+}
+
+private class UnaryBB extends BlackBox {
+  val io = IO(new Bundle {
+    val clock = Input(Clock())
+
+    val ready = Input(Bool())
+    val valid = Output(Bool())
+  })
+}
+
+private class VecOfBoolBB extends BlackBox {
+  val io = IO(new Bundle {
+    val d_in  = Input(Vec(3, Bool()))
+    val d_out = Output(Vec(2, Bool()))
+  })
+}