How to run a single test with Mocha

Question

I use Mocha to test my JavaScript stuff  My test file contains 5 tests  Is that possible to run a specific test  or set of tests  rather than all the tests in the file

User · Answer

Looking into https   mochajs org  usage we see that simply use      mocha test myfile   will work  You can omit the   js  at the end

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If you are using npm test  using package json scripts  use an extra -- to pass the param through to mocha  e g  npm test -- --grep  my second test   EDIT  Looks like --grep can be a little fussy  probably depending on the other arguments   You can   Modify the package json    test mocha    mocha --grep    lt DealsList   gt          Or alternatively use --bail which seems to be less fussy  npm test -- --bail

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npm test  lt filepath gt    eg     npm test test api controllers test js   here  test api controllers test js  is filepath

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run single test    by filename     Actually  one can also run a single mocha test by filename  not just by    it  -string-grepping     if you remove the glob pattern  e g    test      spec js  from your mocha opts  respectively create a copy  without   node modules  bin mocha --opts test mocha single opts test self-test spec js   Here s my mocha single opts  it s only different in missing the aforementioned glob line   --require   test common js --compilers js babel-core register --reporter list --recursive   Background  While you can override the various switches from the opts-File  starting with --  you can t override the glob  That link also has  some explanations   Hint  if node modules  bin mocha confuses you  to use the local package mocha  You can also write just mocha  if you have it installed globally     And if you want the comforts of package json  Still  remove the     -ish glob from your mocha opts  insert them here  for the all-testing  leave them away for the single testing    test    mocha   test      spec js    test-watch    mocha -R list -w   test      spec js    test-single    mocha  1    test-single-watch    mocha -R list -w  1     usage    gt  npm run test   respectively   gt  npm run test-single -- test ES6 self-test spec js     mind the --

User · Answer

Not sure why the grep method is not working for me when using npm test  This works though  I also need to specify the test folder also for some reason  npm test -- test sometest js

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For those who are looking to run a single file but they cannot make it work  what worked for me was that I needed to wrap my test cases in a describe suite as below and then use the describe title e g   My Test Description  as pattern  describe  My Test Description        gt      it  test case 1        gt           My test code        it  test case 2        gt         My test code          then run yarn test -g  quot My Test Description quot  or npm run test -g  quot My Test Description quot

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Hi above solutions didn t work for me   The other way of running a single test is  mocha test cartcheckout checkout js -g  Test Name Goes here    This helps to run a test case from a single file and with specific name

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You can try  it only    it only  Test one         gt                 expect x  to equal y               it  Test two         gt                 expect x  to equal y                 in this the first one only will execute

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Consolidate all your tests in one test js file  amp  your package json add scripts as      scripts        api test    node modules  bin mocha --timeout 10000 --recursive api test        Type command on your test directory    npm run api test

User · Answer

Just use  only before  describe    it  or  context   I run using   npm run test unit   and it executes only units with  only   describe only  get success   function                  it only  should return 1   function

User · Answer

Try using mocha s --grep option       -g  --grep  lt pattern gt             only run tests matching  lt pattern gt    You can use any valid JavaScript regex as  lt pattern gt    For instance  if we have test mytest js   it  logs a   function done      console log  a      done         it  logs b   function done      console log  b      done          Then     mocha -g  logs a    To run a single test  Note that this greps across the names of all describe name  fn  and it name  fn  invocations   Consider using nested describe   calls for namespacing in order to make it easy to locate and select particular sets

User · Answer

Depending on your usage pattern  you might just like to use only  We use the TDD style  it looks like this   test only  Date part of valid Partition Key   function  done                  Only this test will run from all the files suites

[javascript] How to run a single test with Mocha?

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