Add built-in support for deserializing Data from the env

src/helpers/env.rs

@@ -0,0 +1,81 @@
+use envy;
+
+use data::Data;
+use Result;
+
+/// Attempts to deserialize a Data struct from the environment
+pub fn from_env() -> Result<Data> {
+    Ok(envy::from_env()?)
+}
+
+/// Attempts to deserialize a Data struct from the environment. All keys are
+/// prefixed with the given prefix
+pub fn from_env_prefixed(prefix: &str) -> Result<Data> {
+    Ok(envy::prefixed(prefix).from_env()?)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::{
+        env,
+        ops::FnOnce,
+        panic::{catch_unwind, UnwindSafe},
+    };
+
+    fn withenv<F: FnOnce() -> R + UnwindSafe, R>(prefix: Option<&'static str>, test: F) -> R {
+        env::set_var(makekey(prefix, "BASE"), "https://example.com");
+        env::set_var(makekey(prefix, "CLIENT_ID"), "adbc01234");
+        env::set_var(makekey(prefix, "CLIENT_SECRET"), "0987dcba");
+        env::set_var(makekey(prefix, "REDIRECT"), "urn:ietf:wg:oauth:2.0:oob");
+        env::set_var(makekey(prefix, "TOKEN"), "fedc5678");
+
+        let result = catch_unwind(test);
+
+        env::remove_var(makekey(prefix, "BASE"));
+        env::remove_var(makekey(prefix, "CLIENT_ID"));
+        env::remove_var(makekey(prefix, "CLIENT_SECRET"));
+        env::remove_var(makekey(prefix, "REDIRECT"));
+        env::remove_var(makekey(prefix, "TOKEN"));
+
+        fn makekey(prefix: Option<&'static str>, key: &str) -> String {
+            if let Some(prefix) = prefix {
+                format!("{}{}", prefix, key)
+            } else {
+                key.to_string()
+            }
+        }
+
+        result.expect("failed")
+    }
+
+    #[test]
+    fn test_from_env_no_prefix() {
+        let desered = withenv(None, || from_env()).expect("Couldn't deser");
+        assert_eq!(
+            desered,
+            Data {
+                base: "https://example.com".into(),
+                client_id: "adbc01234".into(),
+                client_secret: "0987dcba".into(),
+                redirect: "urn:ietf:wg:oauth:2.0:oob".into(),
+                token: "fedc5678".into(),
+            }
+        );
+    }
+
+    #[test]
+    fn test_from_env_prefixed() {
+        let desered = withenv(Some("APP_"), || from_env_prefixed("APP_")).expect("Couldn't deser");
+        assert_eq!(
+            desered,
+            Data {
+                base: "https://example.com".into(),
+                client_id: "adbc01234".into(),
+                client_secret: "0987dcba".into(),
+                redirect: "urn:ietf:wg:oauth:2.0:oob".into(),
+                token: "fedc5678".into(),
+            }
+        );
+    }
+}

src/helpers/mod.rs

@@ -22,5 +22,17 @@ pub mod toml;
 /// ```
 pub mod json;
 
+#[cfg(feature = "env")]
+/// Helpers for deserializing a `Data` struct from the environment
+///
+/// In order to use this module, set the "env" feature in your Cargo.toml:
+///
+/// ```toml,ignore
+/// [dependencies.elefren]
+/// version = "0.18"
+/// features = ["env"]
+/// ```
+pub mod env;
+
 /// Helpers for working with the command line
 pub mod cli;