Change environment variable syntax to ${VAR} - Fix for #81 (#83)

* Adjust environment variable regex to ${VAR}

* Add replace_env_var_references test

src/util.rs

@@ -76,12 +76,12 @@ pub fn parse_duration(s: &str) -> Result<std::time::Duration> {
     }
 }
 
-/// Replace all env-var references of the format `"something $foo"` in a string
+/// Replace all env-var references of the format `"something ${foo}"` in a string
 /// by the actual env-variables. If the env-var isn't found, will replace the
 /// reference with an empty string.
 pub fn replace_env_var_references(input: String) -> String {
     lazy_static::lazy_static! {
-        static ref ENV_VAR_PATTERN: regex::Regex = regex::Regex::new(r"\$([^\s]*)").unwrap();
+        static ref ENV_VAR_PATTERN: regex::Regex = regex::Regex::new(r"\$\{([^\s]*)\}").unwrap();
     }
     ENV_VAR_PATTERN
         .replace_all(&input, |var_name: &regex::Captures| {
@@ -89,3 +89,19 @@ pub fn replace_env_var_references(input: String) -> String {
         })
         .into_owned()
 }
+
+#[cfg(test)]
+mod test {
+    use super::replace_env_var_references;
+    use std;
+
+    #[test]
+    fn test_replace_env_var_references() {
+        let scss = "$test: ${USER};";
+
+        assert_eq!(
+            replace_env_var_references(String::from(scss)),
+            format!("$test: {};", std::env::var("USER").unwrap_or_default())
+        )
+    }
+}