[ci] run example jupyter notebooks as part of tests at the CI side (#1807)

* execute notebooks on CIs

* run notebooks in interactive mode and increase timeout for MinGW

* hotfix alphabetically sort packages installation

.appveyor.yml

@@ -52,3 +52,6 @@ test_script:
         python $file
         if ($LastExitCode -ne 0) { $host.SetShouldExit($LastExitCode) }
       }  # run all examples
+  - cd %APPVEYOR_BUILD_FOLDER%\examples\python-guide\notebooks
+  - conda install -y -n test-env ipywidgets notebook
+  - jupyter nbconvert --ExecutePreprocessor.timeout=180 --to notebook --execute --inplace *.ipynb  # run all notebooks

.ci/test.sh

@@ -145,4 +145,7 @@ matplotlib.use\(\"Agg\"\)\
 ' plot_example.py  # prevent interactive window mode
     sed -i'.bak' 's/graph.render(view=True)/graph.render(view=False)/' plot_example.py
     for f in *.py; do python $f || exit -1; done  # run all examples
+    cd $BUILD_DIRECTORY/examples/python-guide/notebooks
+    conda install -y -n $CONDA_ENV ipywidgets notebook
+    jupyter nbconvert --ExecutePreprocessor.timeout=180 --to notebook --execute --inplace *.ipynb || exit -1  # run all notebooks
 fi

.ci/test_windows.ps1

@@ -36,4 +36,7 @@ if ($env:TASK -eq "regular") {
   foreach ($file in @(Get-ChildItem *.py)) {
     python $file ; Check-Output $LastExitCode
   }  # run all examples
+  cd $env:BUILD_SOURCESDIRECTORY/examples/python-guide/notebooks
+  conda install -y -n $env:CONDA_ENV ipywidgets notebook
+  jupyter nbconvert --ExecutePreprocessor.timeout=180 --to notebook --execute --inplace *.ipynb ; Check-Output $LastExitCode  # run all notebooks
 }