Add cargo fmt to travis build config

Author: Atul9

.travis.yml

@@ -19,19 +19,26 @@ matrix:
       env: DO_FUZZ=true
     - rust: stable
       env: DO_FUZZ=true
-script: |
-  cargo build --verbose &&
-  cargo test --verbose &&
-  cargo test --verbose --features serde &&
-  ([ $TRAVIS_RUST_VERSION != nightly ] || cargo check --verbose --no-default-features) &&
-  ([ $TRAVIS_RUST_VERSION != nightly ] || cargo test --verbose --features union) &&
-  ([ $TRAVIS_RUST_VERSION != nightly ] || cargo test --verbose --all-features) &&
-  ([ $TRAVIS_RUST_VERSION != nightly ] || cargo bench --verbose bench) &&
-  ([ $TRAVIS_RUST_VERSION != nightly ] || bash ./scripts/run_miri.sh) &&
-  if [ "$DO_FUZZ" = true ]
-  then
-  (
-    cd fuzz
-    ./travis-fuzz.sh
-  )
-  fi
+script:
+  - |
+    if [[ "$TRAVIS_RUST_VERSION" == stable ]]
+    then
+      rustup component add rustfmt
+      cargo fmt --all -- --check
+    fi
+  - |
+    cargo build --verbose &&
+    cargo test --verbose &&
+    cargo test --verbose --features serde &&
+    ([ $TRAVIS_RUST_VERSION != nightly ] || cargo check --verbose --no-default-features) &&
+    ([ $TRAVIS_RUST_VERSION != nightly ] || cargo test --verbose --features union) &&
+    ([ $TRAVIS_RUST_VERSION != nightly ] || cargo test --verbose --all-features) &&
+    ([ $TRAVIS_RUST_VERSION != nightly ] || cargo bench --verbose bench) &&
+    ([ $TRAVIS_RUST_VERSION != nightly ] || bash ./scripts/run_miri.sh) &&
+    if [ "$DO_FUZZ" = true ]
+    then
+    (
+      cd fuzz
+      ./travis-fuzz.sh
+    )
+    fi