simulator: attempt to extract source line.

core/src/main/scala/chisel3/internal/Error.scala

@@ -29,6 +29,28 @@ object ExceptionHelpers {
   def ellipsis(message: Option[String] = None): StackTraceElement =
     new StackTraceElement("..", " ", message.getOrElse(""), -1)
 
+  private[chisel3] def getErrorLineInFile(sourceRoots: Seq[File], sl: SourceLine): List[String] = {
+    def tryFileInSourceRoot(sourceRoot: File): Option[List[String]] = {
+      try {
+        val file = new File(sourceRoot, sl.filename)
+        val lines = Source.fromFile(file).getLines()
+        var i = 0
+        while (i < (sl.line - 1) && lines.hasNext) {
+          lines.next()
+          i += 1
+        }
+        val line = lines.next()
+        val caretLine = (" " * (sl.col - 1)) + "^"
+        Some(line :: caretLine :: Nil)
+      } catch {
+        case scala.util.control.NonFatal(_) => None
+      }
+    }
+    val sourceRootsWithDefault = if (sourceRoots.nonEmpty) sourceRoots else Seq(new File("."))
+    // View allows us to search the directories one at a time and early out
+    sourceRootsWithDefault.view.map(tryFileInSourceRoot(_)).collectFirst { case Some(value) => value }.getOrElse(Nil)
+  }
+
   /** Utility methods that can be added to exceptions.
     */
   implicit class ThrowableHelpers(throwable: Throwable) {
@@ -254,28 +276,6 @@ private[chisel3] class ErrorLog(
   throwOnFirstError: Boolean) {
   import ErrorLog.withColor
 
-  private def getErrorLineInFile(sl: SourceLine): List[String] = {
-    def tryFileInSourceRoot(sourceRoot: File): Option[List[String]] = {
-      try {
-        val file = new File(sourceRoot, sl.filename)
-        val lines = Source.fromFile(file).getLines()
-        var i = 0
-        while (i < (sl.line - 1) && lines.hasNext) {
-          lines.next()
-          i += 1
-        }
-        val line = lines.next()
-        val caretLine = (" " * (sl.col - 1)) + "^"
-        Some(line :: caretLine :: Nil)
-      } catch {
-        case scala.util.control.NonFatal(_) => None
-      }
-    }
-    val sourceRootsWithDefault = if (sourceRoots.nonEmpty) sourceRoots else Seq(new File("."))
-    // View allows us to search the directories one at a time and early out
-    sourceRootsWithDefault.view.map(tryFileInSourceRoot(_)).collectFirst { case Some(value) => value }.getOrElse(Nil)
-  }
-
   /** Returns an appropriate location string for the provided source info.
     * If the source info is of `NoSourceInfo` type, the source location is looked up via stack trace.
     * If the source info is `None`, an empty string is returned.
@@ -292,7 +292,7 @@ private[chisel3] class ErrorLog(
   // id is optional because it has only been applied to warnings, TODO apply to errors
   private def logWarningOrError(msg: String, si: Option[SourceInfo], isFatal: Boolean): Unit = {
     val location = errorLocationString(si)
-    val sourceLineAndCaret = si.collect { case sl: SourceLine => getErrorLineInFile(sl) }.getOrElse(Nil)
+    val sourceLineAndCaret = si.collect { case sl: SourceLine => ExceptionHelpers.getErrorLineInFile(sourceRoots, sl) }.getOrElse(Nil)
     val fullMessage = if (location.isEmpty) msg else s"$location: $msg"
     val errorLines = fullMessage :: sourceLineAndCaret
     val entry = ErrorEntry(errorLines, isFatal)

src/main/scala/chisel3/simulator/PeekPokeAPI.scala

@@ -3,13 +3,18 @@ package chisel3.simulator
 import svsim._
 import chisel3._
 
-import chisel3.experimental.SourceInfo
+import chisel3.experimental.{SourceInfo, SourceLine}
+import chisel3.internal.ExceptionHelpers
 
 object PeekPokeAPI extends PeekPokeAPI
 
 trait PeekPokeAPI {
-  case class FailedExpectationException[T](sourceInfo: SourceInfo, observed: T, expected: T, message: String)
-      extends Exception(s"Failed Expectation: Observed value '$observed' != $expected. $message ${sourceInfo.makeMessage(x => x)}")
+  case class FailedExpectationException[T](sourceInfo: SourceInfo, extraContext: Seq[String], observed: T, expected: T, message: String)
+      extends Exception(
+        s"Failed Expectation: Observed value '$observed' != $expected. " +
+        s"$message ${sourceInfo.makeMessage(x => x)}" +
+        (if (extraContext.nonEmpty) s"\n${extraContext.mkString("\n")}" else "")
+      )
 
   implicit class testableClock(clock: Clock) {
     def step(cycles: Int = 1): Unit = {
@@ -134,10 +139,19 @@ trait PeekPokeAPI {
       val module = AnySimulatedModule.current
       module.willPeek()
       val simulationPort = module.port(data)
+
       simulationPort.check(isSigned = isSigned) { observedValue =>
         val observed = encode(observedValue)
-        if (observed != expected)
-          throw FailedExpectationException(sourceInfo, observed, expected, buildMessage(observed, expected))
+        if (observed != expected) {
+          val extraContext =
+            sourceInfo match {
+              case sl: SourceLine =>
+                ExceptionHelpers.getErrorLineInFile(Seq(), sl)
+              case _ =>
+                Seq()
+            }
+          throw FailedExpectationException(sourceInfo, extraContext, observed, expected, buildMessage(observed, expected))
+        }
       }
     }
   }

src/test/scala/chiselTests/simulator/SimulatorSpec.scala

@@ -73,7 +73,7 @@ class SimulatorSpec extends AnyFunSpec with Matchers {
 
     it("reports failed expects correctly") {
       val simulator = new VerilatorSimulator("test_run_dir/simulator/GCDSimulator")
-      a [PeekPokeAPI.FailedExpectationException[_]] must be thrownBy {
+      val thrown = the [PeekPokeAPI.FailedExpectationException[_]] thrownBy {
         simulator
         .simulate(new GCD()) { module =>
           import PeekPokeAPI._
@@ -87,6 +87,11 @@ class SimulatorSpec extends AnyFunSpec with Matchers {
           gcd.io.result.expect(5)
         }.result
       }
+      thrown.getMessage must include regex "Observed value '12' != 5\\."
+      thrown.getMessage must include regex " @\\[src/test/scala/chiselTests/simulator/SimulatorSpec\\.scala \\d+:\\d+\\]"
+      thrown.getMessage must include regex "gcd\\.io\\.result\\.expect\\(5\\)"
+      // Not actually anchoring this so it's not extremely brittle, only somewhat.
+      thrown.getMessage must include regex "                    \\^"
     }
 
     it("runs a design that includes an external module") {