[PATCH 1/2] travis: Check if docs can be built with multiple Sphinx versions

[Eduardo Habkost <ehabkost@redhat.com>]

Add new jobs to .travis.yml to test if docs can be built with
multiple Sphinx versions: 1.6.1, latest 1.x, 2.0.0, and latest
2.x.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 .travis.yml | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/.travis.yml b/.travis.yml
index 1054ec5d29..f5208301d6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -181,6 +181,43 @@ jobs:
             - perl
 
 
+    # Check we can build docs with multiple Sphinx versions.
+    # We need --sphinx-build=sphinx-build to ensure we use the
+    # sphinx-build binary installed by pip.
+
+    # 1.6.1 is the oldest Sphinx version we support
+    - name: "docs (Sphinx 1.6.1)"
+      env:
+        - CONFIG="--enable-docs --sphinx-build=sphinx-build"
+      install:
+        - pip install -q sphinx==1.6.1
+      script:
+        - make -j${JOBS} sphinxdocs
+    - name: "docs (Sphinx 1.x)"
+      env:
+        - CONFIG="--enable-docs --sphinx-build=sphinx-build"
+      install:
+        # install latest 1.x version
+        - pip install -q 'sphinx>=1.0,<2.0'
+      script:
+        - make -j${JOBS} sphinxdocs
+    - name: "docs (Sphinx 2.0.0)"
+      env:
+        - CONFIG="--enable-docs --sphinx-build=sphinx-build"
+      install:
+        - pip install -q sphinx==2.0.0
+      script:
+        - make -j${JOBS} sphinxdocs
+    - name: "docs (Sphinx 2.x)"
+      env:
+        - CONFIG="--enable-docs --sphinx-build=sphinx-build"
+      install:
+        # install latest 2.x version
+        - pip install -q 'sphinx>=2.0,<3.0'
+      script:
+        - make -j${JOBS} sphinxdocs
+
+
     # Test with Clang for compile portability (Travis uses clang-5.0)
     - name: "Clang (user)"
       env:
-- 
2.28.0