function assertCheckTypes(checker, one, two) {
      chai.assert.isTrue(checker.doTypeChecks(one, two));
      // Order should not matter.
      chai.assert.isTrue(checker.doTypeChecks(one, two));
    }
Assert that the type checks pass for the given connections in either
order.
@param {!Blockly.IConnectionChecker} checker The connection checker
    object.
@param {!Blockly.Connection} one The first connection.
@param {!Blockly.Connection} two The second connection.