Added show module which will eventually show DocDef.

src/action/show.rs

@@ -0,0 +1,37 @@
+use crate::{message::MessageAction, name::NameType};
+
+#[derive(Clone, Debug)]
+pub struct Show {
+    doc_name: NameType,
+}
+
+impl Show {
+    pub fn new<NT>(name: NT) -> Self
+    where
+        NT: Into<NameType>,
+    {
+        Self {
+            doc_name: name.into(),
+        }
+    }
+}
+
+impl MessageAction for Show {
+    fn doc_name(&self) -> &NameType {
+        &self.doc_name
+    }
+}
+
+#[cfg(test)]
+mod shows {
+    use super::*;
+    use crate::name::test_support::random_name;
+
+    #[test]
+    fn can_request_a_show() {
+        let name = random_name();
+        let expected: NameType = name.clone().into();
+        let show = Show::new(name);
+        assert_eq!(show.doc_name(), &expected);
+    }
+}