I created a schema that provides both a test expression and test pattern for the discriminator. As per DFDL-7-69R, this should cause a Schema definition error. However, when running the test I get the following error:

[info] - test_discriminators_discrimInvalidSchema *** FAILED ***
[info] daffodil.exceptions.Abort: Invariant broken. unexpected case.
[info] daffodil.exceptions.Assert$.abort(Assert.scala:53)
[info] daffodil.exceptions.Assert$.invariantFailed(Assert.scala:90)
[info] daffodil.dsom.DFDLAssertionBase.testTxt(DFDLAnnotation.scala:552)
[info] daffodil.processors.AssertPatternBase.<init>(Primitives.scala:2419)
[info] at daffodil.exceptions.Assert$.abort(Assert.scala:53)
[info] at daffodil.exceptions.Assert$.invariantFailed(Assert.scala:90)
[info] at daffodil.dsom.DFDLAssertionBase.testTxt(DFDLAnnotation.scala:552)
[info] at daffodil.processors.AssertPatternBase.<init>(Primitives.scala:2419)
[info] at daffodil.processors.DiscriminatorPatternPrim.<init>(Primitives.scala:2487)
[info] at daffodil.dsom.DFDLDiscriminator.gram(DFDLAnnotation.scala:576)
[info] at daffodil.dsom.DFDLDiscriminator.gram(DFDLAnnotation.scala:572)
[info] at daffodil.dsom.DFDLStatement.diagnosticChildren(DFDLAnnotation.scala:413)
[info] at daffodil.dsom.DiagnosticsProviding$class.isError(ProvidesDiagnostics.scala:150)
[info] at daffodil.dsom.DFDLAnnotation.isError(DFDLAnnotation.scala:20)
[info] ...

The test is currently in:
daffodil-test/src/test/scala-debug/daffodil/section07/discriminators/TestDiscriminatorsDebug.scala

(test_discriminators_discrimInvalidSchema)