Build documentation on TravisCI (#1908)

* test sphinx doc build on travis

* test_env name for all environments

* don't run unit tests on doc build

* fix travis yaml

* semicolons

* sphinx_rtd_theme

* install theme after the activating environment

* fix list formatting in installing.rst

* fail travis doc build only when full errors (not warnings) are found

* flake8 for docs build

Author: Joe Hamman

.travis.yml

@@ -45,6 +45,8 @@ matrix:
     env: CONDA_ENV=py36-rasterio1.0alpha
   - python: 3.6
     env: CONDA_ENV=py36-zarr-dev
+  - python: 3.5
+    env: CONDA_ENV=docs
   allow_failures:
   - python: 3.6
     env:
@@ -86,16 +88,25 @@ before_install:
   - conda info -a
 
 install:
-  - conda env create --file ci/requirements-$CONDA_ENV.yml
+  - if [[ "$CONDA_ENV" == "docs" ]]; then
+      conda env create -n test_env --file doc/environment.yml;
+    else
+      conda env create -n test_env --file ci/requirements-$CONDA_ENV.yml;
+    fi
   - source activate test_env
   - conda list
-  - python setup.py install
+  - pip install --no-deps -e .
   - python xarray/util/print_versions.py
 
 script:
   - flake8 -j auto xarray
   - python -OO -c "import xarray"
-  - py.test xarray --cov=xarray --cov-config ci/.coveragerc --cov-report term-missing --verbose $EXTRA_FLAGS
+  - if [[ "$CONDA_ENV" == "docs" ]]; then
+      conda install -c conda-forge sphinx_rtd_theme;
+      sphinx-build -n -b html -d _build/doctrees doc _build/html;
+    else
+      py.test xarray --cov=xarray --cov-config ci/.coveragerc --cov-report term-missing --verbose $EXTRA_FLAGS;
+    fi
 
 after_success:
   - coveralls

doc/environment.yml

@@ -18,3 +18,4 @@ dependencies:
   - sphinx-gallery
   - zarr
   - iris
+  - flake8

doc/installing.rst

@@ -78,6 +78,7 @@ Testing
 -------
 
 To run the test suite after installing xarray, first install (via pypi or conda)
+
 - `py.test <https://pytest.org>`__: Simple unit testing library
 - `mock <https://pypi.python.org/pypi/mock>`__: additional testing library required for python version 2