     @uneqDateTimesTZ.exec(@ctx).should.be.true()
 
   it 'should identify uncertain/unequal DateTimes when there is imprecision', ->
-    should(@possiblyEqualDateTimes.exec(@ctx)).be.null
+    should(@possiblyEqualDateTimes.exec(@ctx)).be.null()
     @impossiblyEqualDateTimes.exec(@ctx).should.be.true()
 
 describe 'Less', ->

    @aLtB_Quantity_diff.exec(@ctx).should.be.false()

  it 'should be null for 5 Cel > 4 m', ->
    should.not.exist(@aGtB_Quantity_incompatible.exec(@ctx))

  it 'should be null for 5 Cel > 5 m', ->
    should.not.exist(@aEqB_Quantity_incompatible.exec(@ctx))

  it 'should be null for 5 Cel > 40 m', ->
    should.not.exist(@aLtB_Quantity_incompatible.exec(@ctx))


describe 'GreaterOrEqual', ->

    @aLtB_Quantity_diff.exec(@ctx).should.be.true()

  it 'should be null for 5 Cel < 4 m', ->
    should(@aGtB_Quantity_incompatible.exec(@ctx)).be.null()

  it 'should be null for 5 Cel < 5 m', ->
    should(@aEqB_Quantity_incompatible.exec(@ctx)).be.null()

  it 'should be null for 5 Cel < 40 m', ->
    should(@aLtB_Quantity_incompatible.exec(@ctx)).be.null()

describe 'LessOrEqual', ->
  @beforeEach ->
