test: Added integration tests for the ValidateTheme macro

proc_macros/validate_theme_derive/src/lib.rs

@@ -2,6 +2,69 @@ use proc_macro::TokenStream;
 use quote::quote;
 use syn::{parse_macro_input, Data, DeriveInput, Fields};
 
+/// Derive macro for generating a `validate` method for a Theme struct.
+/// The `validate` method ensures that all values with the `validate` attribute are not `None`.
+/// Otherwise, an error message it output to both the log file and stdout and the program exits.
+/// 
+/// # Example
+/// 
+/// Valid themes pass through the program transitively without any messages being output.
+/// 
+/// ```
+/// use validate_theme_derive::ValidateTheme;
+/// 
+/// #[derive(ValidateTheme, Default)]
+/// struct Theme {
+///     pub name: String,
+///     #[validate]
+///     pub good: Option<Style>,
+///     #[validate]
+///     pub bad: Option<Style>,
+///     pub ugly: Option<Style>,
+/// }
+/// 
+/// struct Style {
+/// 	color: String,
+/// }
+/// 
+/// let theme = Theme {
+/// 	good: Some(Style { color: "Green".to_owned() }),
+/// 	bad: Some(Style { color: "Red".to_owned() }),
+/// 	..Theme::default()
+/// };
+/// 
+/// // Since only `good` and `bad` have the `validate` attribute, the `validate` method will only check those fields.
+/// theme.validate();
+/// // Since both `good` and `bad` have values, the program will not exit and no message is output.
+/// ```
+/// 
+/// Invalid themes will output an error message to both the log file and stdout and the program will exit.
+///
+/// ```should_panic
+/// use validate_theme_derive::ValidateTheme;
+///
+/// #[derive(ValidateTheme, Default)]
+/// struct Theme {
+///     pub name: String,
+///     #[validate]
+///     pub good: Option<Style>,
+///     #[validate]
+///     pub bad: Option<Style>,
+///     pub ugly: Option<Style>,
+/// }
+///
+/// struct Style {
+///     color: String,
+/// }
+///
+/// let theme = Theme {
+///     bad: Some(Style { color: "Red".to_owned() }),
+///     ..Theme::default()
+/// };
+/// 
+/// // Since `good` has the `validate` attribute and since `good` is `None`, the `validate` method will output an error message and exit the program.
+/// theme.validate();
+/// ```
 #[proc_macro_derive(ValidateTheme, attributes(validate))]
 pub fn derive_validate_theme(input: TokenStream) -> TokenStream {
 	let input = parse_macro_input!(input as DeriveInput);
@@ -22,8 +85,8 @@ pub fn derive_validate_theme(input: TokenStream) -> TokenStream {
 					validation_checks.push(quote! {
 						if self.#field_name.is_none() {
 							log::error!("{} is missing a color value.", stringify!(#field_name));
-								eprintln!("{} is missing a color value.", stringify!(#field_name));
-								process::exit(1);
+							eprintln!("{} is missing a color value.", stringify!(#field_name));
+							std::process::exit(1);
 						}
 					})
 				}