Tests fail for Node.js >= 12

[nileshpatra]

Sharing the logs:

    ✗ same error for bad prime
     ---
       operator: equal
       expected: 1
       actual:   9
       at: Test.<anonymous> (/home/nilesh/ups/diffie-hellman/test.js:127:5)
     ...
    ✗ same error for bad prime non testable generator
     ---
       operator: equal
       expected: 1
       actual:   5
       at: Test.<anonymous> (/home/nilesh/ups/diffie-hellman/test.js:130:5)
     ...
    ✓ same error for good prime wrong generator
    ✗ same error for good prime non testable generator
     ---
       operator: equal
       expected: 0
       actual:   4
       at: Test.<anonymous> (/home/nilesh/ups/diffie-hellman/test.js:136:5)
     ...
   
  tests 233
  pass  230
  fail  3
   
  Failed Tests: There were 3 failures

    ✗ check errors same error for bad prime
    ✗ check errors same error for bad prime non testable generator
    ✗ check errors same error for good prime non testable generator

npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! [email protected] test: `node test.js | tspec`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the [email protected] test script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/nilesh/.npm/_logs/2020-01-31T15_53_55_954Z-debug.log