Fix #cite autocompletion

crates/typst-ide/src/complete.rs

@@ -1050,7 +1050,7 @@ impl<'a> CompletionContext<'a> {
 
     /// A small window of context before the cursor.
     fn before_window(&self, size: usize) -> &str {
-        Scanner::new(self.before).from(self.cursor.saturating_sub(size))
+        Scanner::new(self.before).get(self.cursor.saturating_sub(size)..self.cursor)
     }
 
     /// Add a prefix and suffix to all applications.
@@ -1455,4 +1455,23 @@ mod tests {
     fn test_autocomplete_before_window_char_boundary() {
         test("😀😀     #text(font: \"\")", -2);
     }
+
+    /// Ensure that autocompletion for `#cite(|)` completes bibligraphy labels,
+    /// but no other labels.
+    #[test]
+    fn test_autocomplete_cite_function() {
+        // First compile a working file to get a document.
+        let mut world = TestWorld::new("#bibliography(\"works.bib\") <bib>")
+            .with_asset_by_name("works.bib");
+        let doc = typst::compile(&world).output.ok();
+
+        // Then, add the invalid `#cite` call. Had the document been invalid
+        // initially, we would have no populated document to autocomplete with.
+        let end = world.main.len_bytes();
+        world.main.edit(end..end, " #cite()");
+
+        test_with_world_and_doc(&world, doc.as_ref(), -1)
+            .must_include(["netwok", "glacier-melt", "supplement"])
+            .must_exclude(["bib"]);
+    }
 }

crates/typst-ide/src/lib.rs

@@ -97,6 +97,8 @@ fn summarize_font_family<'a>(variants: impl Iterator<Item = &'a FontInfo>) -> Ec
 
 #[cfg(test)]
 mod tests {
+    use std::collections::HashMap;
+
     use typst::diag::{FileError, FileResult};
     use typst::foundations::{Bytes, Datetime, Smart};
     use typst::layout::{Abs, Margin, PageElem};
@@ -108,6 +110,7 @@ mod tests {
     /// A world for IDE testing.
     pub struct TestWorld {
         pub main: Source,
+        assets: HashMap<FileId, Bytes>,
         base: &'static TestBase,
     }
 
@@ -120,10 +123,21 @@ mod tests {
             let main = Source::new(Self::main_id(), text.into());
             Self {
                 main,
+                assets: HashMap::new(),
                 base: singleton!(TestBase, TestBase::default()),
             }
         }
 
+        /// Add an additional file to the test world.
+        #[track_caller]
+        pub fn with_asset_by_name(mut self, filename: &str) -> Self {
+            let id = FileId::new(None, VirtualPath::new(filename));
+            let data = typst_dev_assets::get_by_name(filename).unwrap();
+            let bytes = Bytes::from_static(data);
+            self.assets.insert(id, bytes);
+            self
+        }
+
         /// The ID of the main file in a `TestWorld`.
         pub fn main_id() -> FileId {
             *singleton!(FileId, FileId::new(None, VirtualPath::new("main.typ")))
@@ -152,7 +166,10 @@ mod tests {
         }
 
         fn file(&self, id: FileId) -> FileResult<Bytes> {
-            Err(FileError::NotFound(id.vpath().as_rootless_path().into()))
+            match self.assets.get(&id) {
+                Some(bytes) => Ok(bytes.clone()),
+                None => Err(FileError::NotFound(id.vpath().as_rootless_path().into())),
+            }
         }
 
         fn font(&self, index: usize) -> Option<Font> {