Check formatting on code at build time

.travis.yml

@@ -23,10 +23,12 @@ before_script:
 - |
   pip install 'travis-cargo<0.2' --user &&
   export PATH=$HOME/.local/bin:$PATH
+  if [ "$CHECK" = "true" ]; then rustup component add rustfmt ; fi
 
 script:
-- travis-cargo build -- $FEATURES
-- travis-cargo --skip 1.13.0 test -- $FEATURES
+- if [ "$CHECK" = "true" ]; then travis-cargo fmt -- -- --check ; fi
+- if [ "$CHECK" = "" ]; then travis-cargo build -- $FEATURES ; fi
+- if [ "$CHECK" = "" ]; then travis-cargo --skip 1.13.0 test -- $FEATURES ; fi
 
 after_success:
 - travis-cargo --only stable doc
@@ -42,6 +44,9 @@ env:
   - FEATURES=--no-default-features
 
 matrix:
+  include:
+  - env: CHECK=true
+    rust: stable
   exclude:
   - env: FEATURES=--features=backtrace
     rust: 1.13.0

tests/tests.rs

@@ -202,16 +202,19 @@ fn has_backtrace_depending_on_env() {
     use std::path::PathBuf;
     use std::process::Command;
 
-    let cmd_folder = if cfg!(build="debug") {
+    let cmd_folder = if cfg!(build = "debug") {
         "debug"
-    } else if cfg!(build="release") {
+    } else if cfg!(build = "release") {
         "release"
     } else {
         panic!("Unknown build config");
     };
 
     let cmd_path = if cfg!(windows) {
-        PathBuf::from(format!("./target/{}/examples/has_backtrace.exe", cmd_folder))
+        PathBuf::from(format!(
+            "./target/{}/examples/has_backtrace.exe",
+            cmd_folder
+        ))
     } else {
         PathBuf::from(format!("./target/{}/examples/has_backtrace", cmd_folder))
     };