Directory Restructure (#1163)

* Move tests -> testing

* Directory restructure

* Update Cargo.toml during restructure

* Update Makefile during restructure

* Fix arbitrary path

common/test_random_derive/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "test_random_derive"
+version = "0.2.0"
+authors = ["thojest <thojest@gmail.com>"]
+edition = "2018"
+description = "Procedural derive macros for implementation of TestRandom trait"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+syn = "1.0.18"
+quote = "1.0.4"

common/test_random_derive/src/lib.rs

@@ -0,0 +1,61 @@
+extern crate proc_macro;
+
+use crate::proc_macro::TokenStream;
+use quote::quote;
+use syn::{parse_macro_input, DeriveInput};
+
+/// Returns true if some field has an attribute declaring it should be generated from default (not
+/// randomized).
+///
+/// The field attribute is: `#[test_random(default)]`
+fn should_use_default(field: &syn::Field) -> bool {
+    field.attrs.iter().any(|attr| {
+        attr.path.is_ident("test_random") && attr.tokens.to_string().replace(" ", "") == "(default)"
+    })
+}
+
+#[proc_macro_derive(TestRandom, attributes(test_random))]
+pub fn test_random_derive(input: TokenStream) -> TokenStream {
+    let derived_input = parse_macro_input!(input as DeriveInput);
+    let name = &derived_input.ident;
+    let (impl_generics, ty_generics, where_clause) = &derived_input.generics.split_for_impl();
+
+    let struct_data = match &derived_input.data {
+        syn::Data::Struct(s) => s,
+        _ => panic!("test_random_derive only supports structs."),
+    };
+
+    // Build quotes for fields that should be generated and those that should be built from
+    // `Default`.
+    let mut quotes = vec![];
+    for field in &struct_data.fields {
+        match &field.ident {
+            Some(ref ident) => {
+                if should_use_default(field) {
+                    quotes.push(quote! {
+                        #ident: <_>::default(),
+                    });
+                } else {
+                    quotes.push(quote! {
+                        #ident: <_>::random_for_test(rng),
+                    });
+                }
+            }
+            _ => panic!("test_random_derive only supports named struct fields."),
+        };
+    }
+
+    let output = quote! {
+        impl #impl_generics TestRandom for #name #ty_generics #where_clause {
+            fn random_for_test(rng: &mut impl rand::RngCore) -> Self {
+               Self {
+                    #(
+                        #quotes
+                    )*
+               }
+            }
+        }
+    };
+
+    output.into()
+}