3 files changed, 46 insertions, 2 deletions

diff --git a/crates/ra_ide_api/src/completion/complete_scope.rs b/crates/ra_ide_api/src/completion/complete_scope.rs
index 44514ab2b..8674b1e66 100644
--- a/crates/ra_ide_api/src/completion/complete_scope.rs
+++ b/crates/ra_ide_api/src/completion/complete_scope.rs
@@ -111,6 +111,20 @@ mod tests {
     }
 
     #[test]
+    fn completes_extern_prelude() {
+        check_reference_completion(
+            "extern_prelude",
+            r"
+            //- /lib.rs
+            use <|>;
+
+            //- /other_crate/lib.rs
+            // nothing here
+            ",
+        );
+    }
+
+    #[test]
     fn completes_module_items_in_nested_modules() {
         check_reference_completion(
             "module_items_in_nested_modules",
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__extern_prelude.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__extern_prelude.snap
new file mode 100644
index 000000000..d0e3a6188
--- /dev/null
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__extern_prelude.snap
@@ -0,0 +1,22 @@
+---
+created: "2019-02-04T21:08:32.615556587+00:00"
+creator: [email protected]
+expression: kind_completions
+source: crates/ra_ide_api/src/completion/completion_item.rs
+---
+[
+    CompletionItem {
+        completion_kind: Reference,
+        label: "other_crate",
+        kind: Some(
+            Module
+        ),
+        detail: None,
+        documentation: None,
+        lookup: None,
+        insert_text: None,
+        insert_text_format: PlainText,
+        source_range: [4; 4),
+        text_edit: None
+    }
+]
diff --git a/crates/ra_ide_api/src/mock_analysis.rs b/crates/ra_ide_api/src/mock_analysis.rs
index 0f2d22ab2..834b30541 100644
--- a/crates/ra_ide_api/src/mock_analysis.rs
+++ b/crates/ra_ide_api/src/mock_analysis.rs
@@ -86,17 +86,25 @@ impl MockAnalysis {
         let mut change = AnalysisChange::new();
         change.add_root(source_root, true);
         let mut crate_graph = CrateGraph::default();
+        let mut root_crate = None;
         for (i, (path, contents)) in self.files.into_iter().enumerate() {
             assert!(path.starts_with('/'));
             let path = RelativePathBuf::from_path(&path[1..]).unwrap();
             let file_id = FileId(i as u32 + 1);
             if path == "/lib.rs" || path == "/main.rs" {
-                crate_graph.add_crate_root(file_id);
+                root_crate = Some(crate_graph.add_crate_root(file_id));
+            } else if path.ends_with("/lib.rs") {
+                let other_crate = crate_graph.add_crate_root(file_id);
+                let crate_name = path.parent().unwrap().file_name().unwrap();
+                if let Some(root_crate) = root_crate {
+                    crate_graph
+                        .add_dep(root_crate, crate_name.into(), other_crate)
+                        .unwrap();
+                }
             }
             change.add_file(source_root, file_id, path, Arc::new(contents));
         }
         change.set_crate_graph(crate_graph);
-        // change.set_file_resolver(Arc::new(file_map));
         host.apply_change(change);
         host
     }