Travis CI - skip unit tests for documentation changes (#5267)

* Add script to skip tests on non master branches with only docs changes

* Review comments - Use 'grep -c' instead of 'wc -l'

.travis.yml

@@ -21,7 +21,7 @@ before_script:
   - avr-gcc --version
 script:
 - git rev-parse --short HEAD
-- make test:all
+- bash util/travis_test.sh
 - bash util/travis_build.sh
 - bash util/travis_docs.sh
 addons:

util/travis_test.sh

@@ -0,0 +1,22 @@
+#!/bin/bash
+
+TRAVIS_COMMIT_MESSAGE="${TRAVIS_COMMIT_MESSAGE:-none}"
+TRAVIS_COMMIT_RANGE="${TRAVIS_COMMIT_RANGE:-HEAD~1..HEAD}"
+
+# test force push
+#TRAVIS_COMMIT_RANGE="c287f1bfc5c8...81f62atc4c1d"
+
+NUM_IMPACTING_CHANGES=$(git diff --name-only -n 1 ${TRAVIS_COMMIT_RANGE} | grep -Ecv '^(docs/)')
+BRANCH=$(git rev-parse --abbrev-ref HEAD)
+
+if [[ "$TRAVIS_COMMIT_MESSAGE" == *"[skip test]"* ]]; then
+    echo "Skipping due to commit message"
+    exit 0
+fi
+
+if [ "$BRANCH" != "master" ] && [ "$NUM_IMPACTING_CHANGES" == "0" ]; then
+    echo "Skipping due to changes not impacting tests"
+    exit 0
+fi
+
+make test:all