title: Trouble using Lintr in R
body: <p>This is probably something asinine, but I don't think I've set up <code>lintr</code> properly in Rstudio (0.99.486). I have all options in Preferences > Code > Diagnostics and have <code>lintr</code> loaded in the project's workspace. However, when I run diagnostics I don't receive errors on syntax, assignment, etc. Is there anything I need to do to enable all the default linters?</p>
  
  <p>(Please disabuse me of whatever dumb mistake I've made thus far.)</p>
  
  <pre><code># Sample code; only warnings are for unknown symbol, unexpected
  # tokens, and missing whitespace around binary operator
  testing = function(test1, test2)
  {
    return paste(test, test1)
  }
  test.var = 1+2
  </code></pre>