Add build pieces for Google Test

[Shreeshrii]

copied from https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!topic/tesseract-dev/VLwwGFKtdPA

Ray | Jul 21
I have the OK to "throw the tests over the wall" already. ie provide them in a non-working form.
There are actually very few copyrighted images that would need to be replaced. Most of the tests run on synthetic data, existing test data, or don't require images.

If someone would put together the build pieces necessary to build and run an empty test (using Google test), then I will port at least one example, and then push the rest out.

Ray | Jul 13
There are the order of 50 tests, some of which complete in <1s. Some take ~10mins to run, but very few. You could probably run the whole lot on a single machine in about an hour.

Jul 13 Jeff Breidenbach 
First step is to make a working but empty test for Tesseract under this
framework. Once that exemplar is in place, we can migrate the existing
tests that currently run inside Google.

[Shreeshrii]

Some tests for tesseract using java as part of Quan's tess4j project

https://github.com/nguyenq/tess4j/tree/master/src/test/java/net/sourceforge/tess4j

[Shreeshrii]

https://stackoverflow.com/questions/35998856/how-can-i-use-google-test-with-my-project-that-builds-via-autotools

[stweil]

@theraysmith, pull request #1051 adds the required pieces for GoogleTest.

[theraysmith]

Thanks! I will port one test, and then determine how easy it is to write portable tests that work both inside Google and outside.

…

On Mon, Jul 24, 2017 at 10:51 AM, Stefan Weil ***@***.***> wrote: @theraysmith <https://github.com/theraysmith>, pull request #1051 <#1051> adds the required pieces for GoogleTest. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#1050 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AL056a53GU5T3Bo5ETJ3KJ6XOFSsIQ5Fks5sRNmPgaJpZM4Og8V1> .

-- Ray.

[Shreeshrii]

PR with Makefile.am for unittest

#1088