Travis: test shellcheck as part of Travis

Closes 30065.

.travis.yml

@@ -35,6 +35,7 @@ matrix:
             - sourceline: 'deb https://deb.torproject.org/torproject.org tor-nightly-0.2.9.x-xenial main'
               key_url: 'https://deb.torproject.org/torproject.org/A3C4F0F979CAA22CDBA8F512EE8CBC9E886DDD89.asc'
           packages:
+            - shellcheck
             - tor
       env: TOR="0.2.9-nightly"
     - addons:
@@ -43,6 +44,7 @@ matrix:
             - sourceline: 'deb https://deb.torproject.org/torproject.org tor-nightly-0.3.4.x-xenial main'
               key_url: 'https://deb.torproject.org/torproject.org/A3C4F0F979CAA22CDBA8F512EE8CBC9E886DDD89.asc'
           packages:
+            - shellcheck
             - tor
       env: TOR="0.3.4-nightly"
     ## The current stable release is listed at the end of the file, because
@@ -53,6 +55,7 @@ matrix:
             - sourceline: 'deb https://deb.torproject.org/torproject.org tor-nightly-0.3.5.x-xenial main'
               key_url: 'https://deb.torproject.org/torproject.org/A3C4F0F979CAA22CDBA8F512EE8CBC9E886DDD89.asc'
           packages:
+            - shellcheck
             - tor
       env: TOR="0.3.5-nightly"
     ## The experimental deb line needs to be updated when 0.4.0 becomes stable
@@ -62,6 +65,7 @@ matrix:
             - sourceline: 'deb https://deb.torproject.org/torproject.org tor-experimental-0.4.0.x-xenial main'
               key_url: 'https://deb.torproject.org/torproject.org/A3C4F0F979CAA22CDBA8F512EE8CBC9E886DDD89.asc'
           packages:
+            - shellcheck
             - tor
       env: TOR="0.4.0-nightly"
     - addons:
@@ -70,6 +74,7 @@ matrix:
             - sourceline: 'deb https://deb.torproject.org/torproject.org tor-nightly-master-xenial main'
               key_url: 'https://deb.torproject.org/torproject.org/A3C4F0F979CAA22CDBA8F512EE8CBC9E886DDD89.asc'
           packages:
+            - shellcheck
             - tor
       env: TOR="master-nightly"
     ## Test all supported python releases
@@ -148,10 +153,12 @@ addons:
       - sourceline: 'deb https://deb.torproject.org/torproject.org xenial main'
         key_url: 'https://deb.torproject.org/torproject.org/A3C4F0F979CAA22CDBA8F512EE8CBC9E886DDD89.asc'
     packages:
+      - shellcheck
       - tor
   ## (macOS only)
   homebrew:
     packages:
+      - shellcheck
       - tor
 
 install:
@@ -160,9 +167,11 @@ install:
   - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then dpkg-query --show; fi
   - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew list --versions; fi
   - python --version
+  - shellcheck --version
   - tor --version
 
 script:
+  - tests/shellcheck-tests.sh
   - tools/test-network.sh --allow-failures 1
 
 after_failure: