Set up R package structure and testing infrastructure

[terrytangyuan]

• Set up R package structure
• Set up testing infrastructure and added a couple test utility functions

This is part of #6

[yongtang]

Not familiar with R, though I am wondering if there is a command we could run to invoke the test?

[terrytangyuan]

@yongtang It's devtools::test("path_to_r_package"). I'll prepare a Docker image and write up some instructions in a follow-up PR.

[yongtang]

Wondering if for cosmetic reasons is it possible to change it to tensorflow-io to match python package?

[terrytangyuan]

R package name cannot contain dashes. Also I was trying to be consistent with other existing R interfaces to TF components:

• tf.estimator: https://github.com/rstudio/tfestimators
• tf.dataset: https://github.com/rstudio/tfdatasets

[yongtang]

I tried to install devtools from the default r-base (with DockerHub's r-base (https://hub.docker.com/_/r-base/). After invoking install.packages("devtools", dependencies = TRUE), the dependency fails with:

ERROR: dependencies ‘curl’, ‘httr’, ‘rvest’, ‘xml2’ are not available for package ‘foghorn’
* removing ‘/usr/local/lib/R/site-library/foghorn’
ERROR: dependencies ‘httr’, ‘whoami’ are not available for package ‘rhub’
* removing ‘/usr/local/lib/R/site-library/rhub’
ERROR: dependency ‘xml2’ is not available for package ‘roxygen2’
* removing ‘/usr/local/lib/R/site-library/roxygen2’
ERROR: dependencies ‘git2r’, ‘httr’, ‘usethis’ are not available for package ‘devtools’
* removing ‘/usr/local/lib/R/site-library/devtools’
ERROR: dependencies ‘httr’, ‘openssl’, ‘roxygen2’, ‘rsconnect’, ‘xml2’ are not available for package ‘pkgdown’
* removing ‘/usr/local/lib/R/site-library/pkgdown’

is there any other ways of install devtools?

[terrytangyuan]

@yongtang ERROR: dependencies ‘curl’, ‘httr’, ‘rvest’, ‘xml2’ are not available - this indicates that there are several system dependencies needed. Try installing these before installing devtools: sudo apt-get install build-essential libcurl4-gnutls-dev libxml2-dev libssl-dev.

[yongtang]

Thanks! After installed devtools and testthat, thentensorflow, the devtools::test() worked from R interface.

[yongtang]

LGTM

[yongtang]

It looks like Travis CI also support R. I will take to see if it is possible to invoke R test with Travis CI.

[terrytangyuan]

Yes, Travis is very friendly with R. If you encounter any issues, let me know!