Clock test allows slight variance for amount of real time passage.

test/unit.src.common.clock.spec.js

     let dt = speedTest(ts); 
     expect(count).to.be.gt(ts - d);
     expect(count).to.be.lt(ts + d);
-    expect(dt).to.be.lt(1000);
+    expect(dt).to.be.gt(990);
+    expect(dt).to.be.lt(1010);
   });
 
   it("4Mhz for approx. 1 second", function(){
     let dt = speedTest(ts); 
     expect(count).to.be.gt(ts - d);
     expect(count).to.be.lt(ts + d);
-    expect(dt).to.be.lt(1000);
+    expect(dt).to.be.gt(990);
+    expect(dt).to.be.lt(1010);
   });
 });