Example usage of ng-constant. Replace <...> with appropriate values.

Gruntfile.js

grunt.initConfig({
  ngconstant: {
    <task>: [
      {
        dest: '<destination file>',
        name: '<module name>',
        constants: {
          '<constant name>': '<constant value>',
          '<constant name>': { ... }
          '<constant name>': grunt.file.readJSON('<JSON file>')
          ...
        }
      }
    ]
  },
})

I'd suggest changing the format to pull the options object out of the array:

grunt.initConfig({
  ngconstant: {
    <task>: {
      dest: '<destination file>',
      name: '<module name>',
      constants: {
        '<constant name>': '<constant value>',
        '<constant name>': { ... }
        '<constant name>': grunt.file.readJSON('<JSON file>')
        ...
      }
    }
  },
})

If you leave it in the array, grunt will complain and fail when you run grunt tests in verbose mode (grunt test --verbose).

Oh thanks for sharing! But I do not see any warnings in my grunt test...
Why would grunt complain because it's an array?