private void assertNoOperandReference(int opIndex, Instruction instr) {
		Reference[] refs = instr.getOperandReferences(opIndex);
		assertEquals("No reference on operand " + opIndex, 0, refs.length);
	}
quick and dirty test of the ProgramContextImpl just to see
if the values are being set for specified address range.
The ProgramContextPlugin will be a more complete test
program, with a gui interface to specify the values and
select/highlight an address range.
Ghidra/Features/Base/src/test/java/ghidra/program/util/ConstantPropogationReferenceTest.java