With working test now

src/consts.rs

@@ -1,6 +1,4 @@
-#[cfg(test)]
 use rustc::lint::Context;
-
 use rustc::middle::const_eval::lookup_const_by_id;
 use rustc::middle::def::PathResolution;
 use rustc::middle::def::Def::*;
@@ -12,9 +10,6 @@ use std::ops::Deref;
 use self::ConstantVariant::*;
 use self::FloatWidth::*;
 
-#[cfg(not(test))]
-pub struct Context;
-
 #[derive(PartialEq, Eq, Debug, Copy, Clone)]
 pub enum FloatWidth {
     Fw32,
@@ -33,8 +28,8 @@ impl From<FloatTy> for FloatWidth {
 
 #[derive(PartialEq, Eq, Debug, Clone)]
 pub struct Constant {
-    constant: ConstantVariant,
-    needed_resolution: bool
+    pub constant: ConstantVariant,
+    pub needed_resolution: bool
 }
 
 impl Constant {
@@ -187,11 +182,7 @@ fn constant_tup<E: Deref<Target=Expr> + Sized>(cx: &Context, tup: &[E]) -> Optio
     })
 }
 
-#[cfg(test)]
-fn fetch_path(_cx: &Context, _expr: &Expr) -> Option<Constant> { None }
-
 /// lookup a possibly constant expression from a ExprPath
-#[cfg(not(test))]
 fn fetch_path(cx: &Context, e: &Expr) -> Option<Constant> {
     if let Some(&PathResolution { base_def: DefConst(id), ..}) =
             cx.tcx.def_map.borrow().get(&e.id) {

tests/consts.rs

@@ -1,11 +1,34 @@
+#![allow(plugin_as_library)]
+#![feature(rustc_private)]
 
 extern crate clippy;
+extern crate syntax;
+extern crate rustc;
 
-use clippy::consts;
+use clippy::consts::constant;
+use clippy::consts::ConstantVariant::*;
 use syntax::ast::*;
+use syntax::ptr::P;
+use syntax::codemap::{Spanned, COMMAND_LINE_SP};
+use std::mem;
+use rustc::lint::Context;
+
+fn ctx() -> &'static Context<'static, 'static> {
+	unsafe { 
+		let x : *const Context<'static, 'static> = std::ptr::null();
+		mem::transmute(x)
+	}
+}
 
 #[test]
 fn test_lit() {
-    assert_eq!(ConstantBool(true), constant(&Context,
-        Expr{ node_id: 1, node: ExprLit(LitBool(true)), span: default() }));
+    assert_eq!(Some(ConstantBool(true)), constant(ctx(),
+        &Expr{ 
+			id: 1, 
+			node: ExprLit(P(Spanned{ 
+				node: LitBool(true), 
+				span: COMMAND_LINE_SP,
+			})), 
+			span: COMMAND_LINE_SP,
+		}).map(|x| x.constant));
 }