Write a couple tests for the core library

_workspace.iml

@@ -4,6 +4,7 @@
     <exclude-output />
     <content url="file://$MODULE_DIR$">
       <sourceFolder url="file://$MODULE_DIR$/micronfig/src" isTestSource="false" />
+      <sourceFolder url="file://$MODULE_DIR$/micronfig/tests" isTestSource="true" />
       <excludeFolder url="file://$MODULE_DIR$/target" />
     </content>
     <orderEntry type="inheritedJdk" />

micronfig/Cargo.toml

@@ -22,3 +22,6 @@ envdot = ["regex"]
 [dependencies]
 micronfig_macros = { version = "0.3.0", path = "../micronfig_macros" }
 regex = { version = "1.10.2", optional = true }
+
+[dev-dependencies]
+tempfile = { version = "3.9.0" }

micronfig/src/envfiles.rs

@@ -21,3 +21,34 @@ pub fn get(key: &OsStr) -> Option<String> {
 
 	Some(data)
 }
+
+
+#[cfg(test)]
+pub(crate) mod tests {
+	use super::*;
+	use crate::testing::tempfile_fixture;
+
+	#[test]
+	fn it_works() {
+		let file = tempfile_fixture("XYZ");
+		std::env::set_var("LETTERS_FILE", file.as_os_str());
+
+		let value = get("LETTERS".as_ref());
+		assert_eq!(value, Some("XYZ".to_string()));
+	}
+
+	#[test]
+	fn missing_envvar() {
+		std::env::remove_var("THIS_ENVVAR_DOES_NOT_EXIST_FILE");
+		let value = get("THIS_ENVVAR_DOES_NOT_EXIST".as_ref());
+		assert_eq!(value, None)
+	}
+
+	#[test]
+	#[should_panic]
+	fn missing_file() {
+		std::env::set_var("NONEXISTENT_FILE", "/this/file/does/not/exist");
+		let value = get("NONEXISTENT".as_ref());
+		println!("{:?}", value);
+	}
+}

micronfig/src/envvars.rs

@@ -6,3 +6,23 @@ use std::ffi::OsStr;
 pub fn get(key: &OsStr) -> Option<String> {
 	std::env::var(key).ok()
 }
+
+
+#[cfg(test)]
+pub(crate) mod tests {
+	use super::*;
+
+	#[test]
+	fn it_works() {
+		std::env::set_var("LETTERS", "XYZ");
+		let value = get("LETTERS".as_ref());
+		assert_eq!(value, Some("XYZ".to_string()));
+	}
+
+	#[test]
+	fn missing_envvar() {
+		std::env::remove_var("THIS_ENVVAR_DOES_NOT_EXIST");
+		let value = get("THIS_ENVVAR_DOES_NOT_EXIST".as_ref());
+		assert_eq!(value, None);
+	}
+}

micronfig/src/lib.rs

@@ -6,5 +6,7 @@ pub mod envvars;
 pub mod envfiles;
 #[cfg(feature = "envdot")]
 pub mod envdot;
+#[cfg(test)]
+mod testing;
 
 pub use micronfig_macros::config;

micronfig/src/testing.rs

@@ -0,0 +1,11 @@
+pub fn tempfile_fixture(content: &str) -> tempfile::TempPath {
+	use std::io::Write;
+
+	let mut file = tempfile::NamedTempFile::new()
+		.expect("the tempfile fixture to be created successfully");
+	write!(file, "{}", content)
+		.expect("to be able to write into the tempfile fixture");
+
+	file.into_temp_path()
+}
+

micronfig_macros/src/lib.rs

@@ -182,8 +182,8 @@ pub fn config(input: TokenStream) -> TokenStream {
 			#[allow(non_snake_case)]
 			pub(crate) fn #identifier() -> &'static #type_final_option {
 				#identifier::_lock.get_or_init(|| {
-					let key: std::ffi::OsString = #identifier_string.into();
-					let value: Option<std::string::String> = _cache().get(&key);
+					let key = #identifier_string.as_ref();
+					let value: Option<std::string::String> = _cache().get(key);
 
 					#require_code
 					#conversion_code