Add tox command for npm test

Author: bjk7119

tox.ini

@@ -51,6 +51,7 @@ commands =
    # Test for Pypi
   fosslight_dependency -p tests/test_pypi -o tests/result/pip
   # Test for NPM (without optional command)
+  npm install --prefix {toxworkdir}/test_npm1 -g license-checker
   fosslight_dependency -p tests/test_npm1 -o tests/result/npm1
   # Test for NPM (with optional command)
   npm install --prefix {toxworkdir}/test_npm2 -g license-checker