Add test crate to check if all the generated items have an associated doc

Author: Yamakaky

test-doc/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "test-doc"
+version = "0.1.0"
+authors = ["yamakaky"]
+
+[dependencies]
+error-chain = { path = ".." }

test-doc/src/lib.rs

@@ -0,0 +1,22 @@
+#[macro_use]
+extern crate error_chain;
+
+/// This module is used to check that all generated items are documented.
+#[deny(missing_docs)]
+pub mod doc {
+    pub mod inner {
+        error_chain! {
+        }
+    }
+
+    error_chain! {
+        links {
+            inner::Error, Test;
+        }
+        errors {
+            Test2 {
+
+            }
+        }
+    }
+}