This PR:
1. Suppress all known warnings.
2. Cleanup test cases and fix some errors in test cases.
3. Fix errors in HiveContext related test cases. These test cases are actually not run previously due to a bug of creating TestHiveContext.
4. Support 'testthat' package version 0.11.0 which prefers that test cases be under 'tests/testthat'
5. Make sure the default Hadoop file system is local when running test cases.
6. Turn on warnings into errors.
Author: Sun Rui <rui.sun@intel.com>
Closes#10030 from sun-rui/SPARK-12034.
Otherwise, `sparkR.init()` with multiple `sparkPackages` results in this warning:
```
Warning message:
In if (packages != "") { :
the condition has length > 1 and only the first element will be used
```
Author: trestletech <jeff.allen@trestletechnology.net>
Closes#7701 from trestletech/compare-packages and squashes the following commits:
72c8b36 [trestletech] Correct function name.
c52db0e [trestletech] Added test for multiple packages.
3aab1a7 [trestletech] Use vector-friendly comparison for packages argument.
Author: Holden Karau <holden@pigscanfly.ca>
Closes#6928 from holdenk/SPARK-8506-sparkr-does-not-provide-an-easy-way-to-depend-on-spark-packages-when-performing-init-from-inside-of-r and squashes the following commits:
b60dd63 [Holden Karau] Add an example with the spark-csv package
fa8bc92 [Holden Karau] typo: sparm -> spark
865a90c [Holden Karau] strip spaces for comparision
c7a4471 [Holden Karau] Add some documentation
c1a9233 [Holden Karau] refactor for testing
c818556 [Holden Karau] Add pakages to R
