fix length comparisons on xxxToProps functions

[planetcohen]

Testing finalMap{State|Dispatch}ToProps.length > 1 breaks when these functions are wrapped in generic decorator functions. Instead, test for !== 1.

For example, let's say I wanted to write a decorator function that logs function invocation like so:

function traceExecution(fn) {
  const name = fn.name;
  return function() {
    console.log('ENTER: ', name);
    const result = fn.apply(this, arguments);
    console.log('LEAVE: ', name, ' --> ', result);
    return result;
  }
}

Then, I want to wrap my mapStateToProps and mapDispatchToProps functions with traceExecution and pass it to connect:

function mapStateToProps(state, props) { /* stuff here */}
function mapDispatchToProps(dispatch, props) { /* stuff here */}
const connector = connect(traceExecution(mapStateToProps), traceExecution(mapDispatchToProps))

This would not work without these fixes, since the functions returned by the decorator have arity 0 and would fail the "> 1" length test.

By changing the arity test to be "!== 1" instead of "> 1", you enable this scenario to work as expected.

[gaearon]

Fair enough. Mind adding tests for this?

[planetcohen]

Done - I added tests checking for expected behavior when arity is zero.

[gaearon]

Thanks!