[ci] add if-else job to Travis

[StrikerRUS]

To be honest, I have no idea when it was lost from there.

[jameslamb]

@StrikerRUS what does if-else task do?

Anyway, looks good to me! The only thing failing on Travis is the check-docs task, link checker is getting a 502 from https://www.mcs.anl.gov/~thakur/papers/ijhpca-coll.pdf

[StrikerRUS]

@jameslamb

Anyway, looks good to me! The only thing failing on Travis is the check-docs task, link checker is getting a 502 from https://www.mcs.anl.gov/~thakur/papers/ijhpca-coll.pdf

Thanks for your review! Yeah, this site is down again. 😠 I think till Monday, based on the previous experience.

what does if-else task do?

It converts a model, refer to
https://lightgbm.readthedocs.io/en/latest/Parameters.html#convert_model

LightGBM/.ci/test.sh

Lines 60 to 67 in b6d4ad8

	if [[ $TASK == "if-else" ]]; then
	conda install -q -y -n $CONDA_ENV numpy
	mkdir $BUILD_DIRECTORY/build && cd $BUILD_DIRECTORY/build && cmake "${CMAKE_OPTS[@]}" .. && make lightgbm -j4 || exit -1
	cd $BUILD_DIRECTORY/tests/cpp_test && ../../lightgbm config=train.conf convert_model_language=cpp convert_model=../../src/boosting/gbdt_prediction.cpp && ../../lightgbm config=predict.conf output_result=origin.pred || exit -1
	cd $BUILD_DIRECTORY/build && make lightgbm -j4 || exit -1
	cd $BUILD_DIRECTORY/tests/cpp_test && ../../lightgbm config=predict.conf output_result=ifelse.pred && python test.py || exit -1
	exit 0
	fi

[StrikerRUS]

Close-reopen for CI.