1 files changed, 124 insertions, 6 deletions
diff --git a/macros/src/declare_interface_args.rs b/macros/src/declare_interface_args.rs
index 529a114..bc15d2e 100644
--- a/macros/src/declare_interface_args.rs
+++ b/macros/src/declare_interface_args.rs
@@ -1,4 +1,4 @@
-use syn::parse::{Parse, ParseStream, Result};
+use syn::parse::{Parse, ParseStream};
 use syn::punctuated::Punctuated;
 use syn::{Token, TypePath};
 
@@ -16,7 +16,7 @@ pub struct DeclareInterfaceArgs
 
 impl Parse for DeclareInterfaceArgs
 {
-    fn parse(input: ParseStream) -> Result<Self>
+    fn parse(input: ParseStream) -> syn::Result<Self>
     {
         let implementation: TypePath = input.parse()?;
 
@@ -30,12 +30,11 @@ impl Parse for DeclareInterfaceArgs
             let flags = Punctuated::<MacroFlag, Token![,]>::parse_terminated(input)?;
 
             for flag in &flags {
-                let flag_str = flag.flag.to_string();
+                let flag_name = flag.flag.to_string();
 
-                if !DECLARE_INTERFACE_FLAGS.contains(&flag_str.as_str()) {
+                if !DECLARE_INTERFACE_FLAGS.contains(&flag_name.as_str()) {
                     return Err(input.error(format!(
-                        "Unknown flag '{}'. Expected one of [ {} ]",
-                        flag_str,
+                        "Unknown flag '{flag_name}'. Expected one of [ {} ]",
                         DECLARE_INTERFACE_FLAGS.join(",")
                     )));
                 }
@@ -62,3 +61,122 @@ impl Parse for DeclareInterfaceArgs
         })
     }
 }
+
+#[cfg(test)]
+mod tests
+{
+    use std::error::Error;
+
+    use proc_macro2::Span;
+    use quote::{format_ident, quote};
+    use syn::{parse2, LitBool};
+
+    use super::*;
+    use crate::test_utils;
+
+    #[test]
+    fn can_parse_with_no_flags() -> Result<(), Box<dyn Error>>
+    {
+        let input_args = quote! {
+            Foo -> IFoo
+        };
+
+        let decl_interface_args = parse2::<DeclareInterfaceArgs>(input_args)?;
+
+        assert_eq!(
+            decl_interface_args.implementation,
+            TypePath {
+                qself: None,
+                path: test_utils::create_path(&[test_utils::create_path_segment(
+                    format_ident!("Foo"),
+                    &[]
+                )])
+            }
+        );
+
+        assert_eq!(
+            decl_interface_args.interface,
+            TypePath {
+                qself: None,
+                path: test_utils::create_path(&[test_utils::create_path_segment(
+                    format_ident!("IFoo"),
+                    &[]
+                )])
+            }
+        );
+
+        assert!(decl_interface_args.flags.is_empty());
+
+        Ok(())
+    }
+
+    #[test]
+    fn can_parse_with_flags() -> Result<(), Box<dyn Error>>
+    {
+        let input_args = quote! {
+            Foobar -> IFoobar, async = true
+        };
+
+        let decl_interface_args = parse2::<DeclareInterfaceArgs>(input_args)?;
+
+        assert_eq!(
+            decl_interface_args.implementation,
+            TypePath {
+                qself: None,
+                path: test_utils::create_path(&[test_utils::create_path_segment(
+                    format_ident!("Foobar"),
+                    &[]
+                )])
+            }
+        );
+
+        assert_eq!(
+            decl_interface_args.interface,
+            TypePath {
+                qself: None,
+                path: test_utils::create_path(&[test_utils::create_path_segment(
+                    format_ident!("IFoobar"),
+                    &[]
+                )])
+            }
+        );
+
+        assert_eq!(
+            decl_interface_args.flags,
+            Punctuated::from_iter(vec![MacroFlag {
+                flag: format_ident!("async"),
+                is_on: LitBool::new(true, Span::call_site())
+            }])
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    fn cannot_parse_with_invalid_flag()
+    {
+        let input_args = quote! {
+            Foobar -> IFoobar, xyz = false, async = true
+        };
+
+        assert!(matches!(parse2::<DeclareInterfaceArgs>(input_args), Err(_)));
+    }
+
+    #[test]
+    fn cannot_parse_with_duplicate_flag()
+    {
+        assert!(matches!(
+            parse2::<DeclareInterfaceArgs>(quote! {
+                Foobar -> IFoobar, async = true, async = true
+            }),
+            Err(_)
+        ));
+
+        assert!(matches!(
+            parse2::<DeclareInterfaceArgs>(quote! {
+                Foobar -> IFoobar, async = true, async = false
+            }),
+            Err(_)
+        ));
+    }
+}