diff --git a/crates/copilot/Cargo.toml b/crates/copilot/Cargo.toml
index 52b9c223bd..1c37b6e298 100644
--- a/crates/copilot/Cargo.toml
+++ b/crates/copilot/Cargo.toml
@@ -8,6 +8,17 @@ publish = false
 path = "src/copilot.rs"
 doctest = false
 
+[features]
+test-support = [
+    "client/test-support",
+    "collections/test-support",
+    "gpui/test-support",
+    "language/test-support",
+    "lsp/test-support",
+    "settings/test-support",
+    "util/test-support",
+]
+
 [dependencies]
 collections = { path = "../collections" }
 context_menu = { path = "../context_menu" }
@@ -30,6 +41,7 @@ smol = "1.2.5"
 futures = "0.3"
 
 [dev-dependencies]
+collections = { path = "../collections", features = ["test-support"] }
 gpui = { path = "../gpui", features = ["test-support"] }
 language = { path = "../language", features = ["test-support"] }
 settings = { path = "../settings", features = ["test-support"] }
diff --git a/crates/copilot/src/copilot.rs b/crates/copilot/src/copilot.rs
index bcf3188482..c0c5afc068 100644
--- a/crates/copilot/src/copilot.rs
+++ b/crates/copilot/src/copilot.rs
@@ -1,4 +1,4 @@
-mod request;
+pub mod request;
 mod sign_in;
 
 use anyhow::{anyhow, Context, Result};
@@ -125,12 +125,8 @@ enum CopilotServer {
 
 #[derive(Clone, Debug)]
 enum SignInStatus {
-    Authorized {
-        _user: String,
-    },
-    Unauthorized {
-        _user: String,
-    },
+    Authorized,
+    Unauthorized,
     SigningIn {
         prompt: Option<request::PromptUserDeviceFlow>,
         task: Shared<Task<Result<(), Arc<anyhow::Error>>>>,
@@ -238,6 +234,23 @@ impl Copilot {
         }
     }
 
+    #[cfg(any(test, feature = "test-support"))]
+    pub fn fake(cx: &mut gpui::TestAppContext) -> (ModelHandle<Self>, lsp::FakeLanguageServer) {
+        let (server, fake_server) =
+            LanguageServer::fake("copilot".into(), Default::default(), cx.to_async());
+        let http = util::http::FakeHttpClient::create(|_| async { unreachable!() });
+        let this = cx.add_model(|cx| Self {
+            http: http.clone(),
+            node_runtime: NodeRuntime::new(http, cx.background().clone()),
+            server: CopilotServer::Started {
+                server: Arc::new(server),
+                status: SignInStatus::Authorized,
+                subscriptions_by_buffer_id: Default::default(),
+            },
+        });
+        (this, fake_server)
+    }
+
     fn start_language_server(
         http: Arc<dyn HttpClient>,
         node_runtime: Arc<NodeRuntime>,
@@ -617,14 +630,10 @@ impl Copilot {
     ) {
         if let CopilotServer::Started { status, .. } = &mut self.server {
             *status = match lsp_status {
-                request::SignInStatus::Ok { user }
-                | request::SignInStatus::MaybeOk { user }
-                | request::SignInStatus::AlreadySignedIn { user } => {
-                    SignInStatus::Authorized { _user: user }
-                }
-                request::SignInStatus::NotAuthorized { user } => {
-                    SignInStatus::Unauthorized { _user: user }
-                }
+                request::SignInStatus::Ok { .. }
+                | request::SignInStatus::MaybeOk { .. }
+                | request::SignInStatus::AlreadySignedIn { .. } => SignInStatus::Authorized,
+                request::SignInStatus::NotAuthorized { .. } => SignInStatus::Unauthorized,
                 request::SignInStatus::NotSignedIn => SignInStatus::SignedOut,
             };
             cx.notify();
diff --git a/crates/copilot/src/request.rs b/crates/copilot/src/request.rs
index e946c8f5cc..415f160ea3 100644
--- a/crates/copilot/src/request.rs
+++ b/crates/copilot/src/request.rs
@@ -117,7 +117,7 @@ pub struct GetCompletionsResult {
     pub completions: Vec<Completion>,
 }
 
-#[derive(Debug, Serialize, Deserialize)]
+#[derive(Clone, Debug, Default, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct Completion {
     pub text: String,
diff --git a/crates/editor/Cargo.toml b/crates/editor/Cargo.toml
index ef2489d7ec..82b7082576 100644
--- a/crates/editor/Cargo.toml
+++ b/crates/editor/Cargo.toml
@@ -11,6 +11,7 @@ doctest = false
 [features]
 test-support = [
     "rand",
+    "copilot/test-support",
     "text/test-support",
     "language/test-support",
     "gpui/test-support",
@@ -65,6 +66,7 @@ tree-sitter-javascript = { version = "*", optional = true }
 tree-sitter-typescript = { git = "https://github.com/tree-sitter/tree-sitter-typescript", rev = "5d20856f34315b068c41edaee2ac8a100081d259", optional = true }
 
 [dev-dependencies]
+copilot = { path = "../copilot", features = ["test-support"] }
 text = { path = "../text", features = ["test-support"] }
 language = { path = "../language", features = ["test-support"] }
 lsp = { path = "../lsp", features = ["test-support"] }
diff --git a/crates/editor/src/editor.rs b/crates/editor/src/editor.rs
index 84d18bafe8..dd32d7420c 100644
--- a/crates/editor/src/editor.rs
+++ b/crates/editor/src/editor.rs
@@ -95,6 +95,7 @@ const CURSOR_BLINK_INTERVAL: Duration = Duration::from_millis(500);
 const MAX_LINE_LEN: usize = 1024;
 const MIN_NAVIGATION_HISTORY_ROW_DELTA: i64 = 10;
 const MAX_SELECTION_HISTORY_LEN: usize = 1024;
+const COPILOT_DEBOUNCE_TIMEOUT: Duration = Duration::from_millis(75);
 
 pub const FORMAT_TIMEOUT: Duration = Duration::from_secs(2);
 
@@ -2799,7 +2800,7 @@ impl Editor {
         let (buffer, buffer_position) =
             self.buffer.read(cx).text_anchor_for_position(cursor, cx)?;
         self.copilot_state.pending_refresh = cx.spawn_weak(|this, mut cx| async move {
-            cx.background().timer(Duration::from_millis(75)).await;
+            cx.background().timer(COPILOT_DEBOUNCE_TIMEOUT).await;
             let (completion, completions_cycling) = copilot.update(&mut cx, |copilot, cx| {
                 (
                     copilot.completions(&buffer, buffer_position, cx),
diff --git a/crates/editor/src/editor_tests.rs b/crates/editor/src/editor_tests.rs
index 292c24f79a..7f7f7ec7ed 100644
--- a/crates/editor/src/editor_tests.rs
+++ b/crates/editor/src/editor_tests.rs
@@ -16,7 +16,7 @@ use language::{BracketPairConfig, FakeLspAdapter, LanguageConfig, LanguageRegist
 use parking_lot::Mutex;
 use project::FakeFs;
 use settings::EditorSettings;
-use std::{cell::RefCell, rc::Rc, time::Instant};
+use std::{cell::RefCell, future::Future, rc::Rc, time::Instant};
 use unindent::Unindent;
 use util::{
     assert_set_eq,
@@ -4585,81 +4585,6 @@ async fn test_completion(cx: &mut gpui::TestAppContext) {
     cx.assert_editor_state("editor.closeˇ");
     handle_resolve_completion_request(&mut cx, None).await;
     apply_additional_edits.await.unwrap();
-
-    // Handle completion request passing a marked string specifying where the completion
-    // should be triggered from using '|' character, what range should be replaced, and what completions
-    // should be returned using '<' and '>' to delimit the range
-    async fn handle_completion_request<'a>(
-        cx: &mut EditorLspTestContext<'a>,
-        marked_string: &str,
-        completions: Vec<&'static str>,
-    ) {
-        let complete_from_marker: TextRangeMarker = '|'.into();
-        let replace_range_marker: TextRangeMarker = ('<', '>').into();
-        let (_, mut marked_ranges) = marked_text_ranges_by(
-            marked_string,
-            vec![complete_from_marker.clone(), replace_range_marker.clone()],
-        );
-
-        let complete_from_position =
-            cx.to_lsp(marked_ranges.remove(&complete_from_marker).unwrap()[0].start);
-        let replace_range =
-            cx.to_lsp_range(marked_ranges.remove(&replace_range_marker).unwrap()[0].clone());
-
-        cx.handle_request::<lsp::request::Completion, _, _>(move |url, params, _| {
-            let completions = completions.clone();
-            async move {
-                assert_eq!(params.text_document_position.text_document.uri, url.clone());
-                assert_eq!(
-                    params.text_document_position.position,
-                    complete_from_position
-                );
-                Ok(Some(lsp::CompletionResponse::Array(
-                    completions
-                        .iter()
-                        .map(|completion_text| lsp::CompletionItem {
-                            label: completion_text.to_string(),
-                            text_edit: Some(lsp::CompletionTextEdit::Edit(lsp::TextEdit {
-                                range: replace_range,
-                                new_text: completion_text.to_string(),
-                            })),
-                            ..Default::default()
-                        })
-                        .collect(),
-                )))
-            }
-        })
-        .next()
-        .await;
-    }
-
-    async fn handle_resolve_completion_request<'a>(
-        cx: &mut EditorLspTestContext<'a>,
-        edits: Option<Vec<(&'static str, &'static str)>>,
-    ) {
-        let edits = edits.map(|edits| {
-            edits
-                .iter()
-                .map(|(marked_string, new_text)| {
-                    let (_, marked_ranges) = marked_text_ranges(marked_string, false);
-                    let replace_range = cx.to_lsp_range(marked_ranges[0].clone());
-                    lsp::TextEdit::new(replace_range, new_text.to_string())
-                })
-                .collect::<Vec<_>>()
-        });
-
-        cx.handle_request::<lsp::request::ResolveCompletionItem, _, _>(move |_, _, _| {
-            let edits = edits.clone();
-            async move {
-                Ok(lsp::CompletionItem {
-                    additional_text_edits: edits,
-                    ..Default::default()
-                })
-            }
-        })
-        .next()
-        .await;
-    }
 }
 
 #[gpui::test]
@@ -5956,6 +5881,160 @@ async fn test_move_to_enclosing_bracket(cx: &mut gpui::TestAppContext) {
     );
 }
 
+#[gpui::test]
+async fn test_copilot(deterministic: Arc<Deterministic>, cx: &mut gpui::TestAppContext) {
+    let (copilot, copilot_lsp) = Copilot::fake(cx);
+    cx.update(|cx| cx.set_global(copilot));
+    let mut cx = EditorLspTestContext::new_rust(
+        lsp::ServerCapabilities {
+            completion_provider: Some(lsp::CompletionOptions {
+                trigger_characters: Some(vec![".".to_string(), ":".to_string()]),
+                ..Default::default()
+            }),
+            ..Default::default()
+        },
+        cx,
+    )
+    .await;
+
+    cx.set_state(indoc! {"
+        oneˇ
+        two
+        three
+    "});
+
+    // When inserting, ensure autocompletion is favored over Copilot suggestions.
+    cx.simulate_keystroke(".");
+    let _ = handle_completion_request(
+        &mut cx,
+        indoc! {"
+            one.|<>
+            two
+            three
+        "},
+        vec!["completion_a", "completion_b"],
+    );
+    handle_copilot_completion_request(
+        &copilot_lsp,
+        vec![copilot::request::Completion {
+            text: "copilot1".into(),
+            position: lsp::Position::new(0, 5),
+            range: lsp::Range::new(lsp::Position::new(0, 0), lsp::Position::new(0, 5)),
+            ..Default::default()
+        }],
+        vec![],
+    );
+    deterministic.advance_clock(COPILOT_DEBOUNCE_TIMEOUT);
+    cx.update_editor(|editor, cx| {
+        assert!(editor.context_menu_visible());
+        assert!(!editor.has_active_copilot_suggestion(cx));
+
+        // Confirming a completion inserts it and hides the context menu, without showing
+        // the copilot suggestion afterwards.
+        editor
+            .confirm_completion(&Default::default(), cx)
+            .unwrap()
+            .detach();
+        assert!(!editor.context_menu_visible());
+        assert!(!editor.has_active_copilot_suggestion(cx));
+        assert_eq!(editor.text(cx), "one.completion_a\ntwo\nthree\n");
+        assert_eq!(editor.display_text(cx), "one.completion_a\ntwo\nthree\n");
+    });
+
+    cx.set_state(indoc! {"
+        oneˇ
+        two
+        three
+    "});
+
+    // When inserting, ensure autocompletion is favored over Copilot suggestions.
+    cx.simulate_keystroke(".");
+    let _ = handle_completion_request(
+        &mut cx,
+        indoc! {"
+            one.|<>
+            two
+            three
+        "},
+        vec!["completion_a", "completion_b"],
+    );
+    handle_copilot_completion_request(
+        &copilot_lsp,
+        vec![copilot::request::Completion {
+            text: "one.copilot1".into(),
+            position: lsp::Position::new(0, 4),
+            range: lsp::Range::new(lsp::Position::new(0, 0), lsp::Position::new(0, 4)),
+            ..Default::default()
+        }],
+        vec![],
+    );
+    deterministic.advance_clock(COPILOT_DEBOUNCE_TIMEOUT);
+    cx.update_editor(|editor, cx| {
+        assert!(editor.context_menu_visible());
+        assert!(!editor.has_active_copilot_suggestion(cx));
+
+        // When hiding the context menu, the Copilot suggestion becomes visible.
+        editor.hide_context_menu(cx);
+        assert!(!editor.context_menu_visible());
+        assert!(editor.has_active_copilot_suggestion(cx));
+        assert_eq!(editor.display_text(cx), "one.copilot1\ntwo\nthree\n");
+        assert_eq!(editor.text(cx), "one.\ntwo\nthree\n");
+    });
+
+    // Ensure existing completion is interpolated when inserting again.
+    cx.simulate_keystroke("c");
+    deterministic.run_until_parked();
+    cx.update_editor(|editor, cx| {
+        assert!(!editor.context_menu_visible());
+        assert!(editor.has_active_copilot_suggestion(cx));
+        assert_eq!(editor.display_text(cx), "one.copilot1\ntwo\nthree\n");
+        assert_eq!(editor.text(cx), "one.c\ntwo\nthree\n");
+    });
+
+    // After debouncing, new Copilot completions should be requested.
+    handle_copilot_completion_request(
+        &copilot_lsp,
+        vec![copilot::request::Completion {
+            text: "one.copilot2".into(),
+            position: lsp::Position::new(0, 5),
+            range: lsp::Range::new(lsp::Position::new(0, 0), lsp::Position::new(0, 5)),
+            ..Default::default()
+        }],
+        vec![],
+    );
+    deterministic.advance_clock(COPILOT_DEBOUNCE_TIMEOUT);
+    cx.update_editor(|editor, cx| {
+        assert!(!editor.context_menu_visible());
+        assert!(editor.has_active_copilot_suggestion(cx));
+        assert_eq!(editor.display_text(cx), "one.copilot2\ntwo\nthree\n");
+        assert_eq!(editor.text(cx), "one.c\ntwo\nthree\n");
+
+        // Canceling should remove the active Copilot suggestion.
+        editor.cancel(&Default::default(), cx);
+        assert!(!editor.has_active_copilot_suggestion(cx));
+        assert_eq!(editor.display_text(cx), "one.c\ntwo\nthree\n");
+        assert_eq!(editor.text(cx), "one.c\ntwo\nthree\n");
+
+        // After canceling, tabbing shouldn't insert the previously shown suggestion.
+        editor.tab(&Default::default(), cx);
+        assert!(!editor.has_active_copilot_suggestion(cx));
+        assert_eq!(editor.display_text(cx), "one.c   \ntwo\nthree\n");
+        assert_eq!(editor.text(cx), "one.c   \ntwo\nthree\n");
+
+        // When undoing the previously active suggestion is shown again.
+        editor.undo(&Default::default(), cx);
+        assert!(editor.has_active_copilot_suggestion(cx));
+        assert_eq!(editor.display_text(cx), "one.copilot2\ntwo\nthree\n");
+        assert_eq!(editor.text(cx), "one.c\ntwo\nthree\n");
+
+        // Tabbing when there is an active suggestion inserts it.
+        editor.tab(&Default::default(), cx);
+        assert!(!editor.has_active_copilot_suggestion(cx));
+        assert_eq!(editor.display_text(cx), "one.copilot2\ntwo\nthree\n");
+        assert_eq!(editor.text(cx), "one.copilot2\ntwo\nthree\n");
+    });
+}
+
 fn empty_range(row: usize, column: usize) -> Range<DisplayPoint> {
     let point = DisplayPoint::new(row as u32, column as u32);
     point..point
@@ -5971,3 +6050,106 @@ fn assert_selection_ranges(marked_text: &str, view: &mut Editor, cx: &mut ViewCo
         marked_text
     );
 }
+
+/// Handle completion request passing a marked string specifying where the completion
+/// should be triggered from using '|' character, what range should be replaced, and what completions
+/// should be returned using '<' and '>' to delimit the range
+fn handle_completion_request<'a>(
+    cx: &mut EditorLspTestContext<'a>,
+    marked_string: &str,
+    completions: Vec<&'static str>,
+) -> impl Future<Output = ()> {
+    let complete_from_marker: TextRangeMarker = '|'.into();
+    let replace_range_marker: TextRangeMarker = ('<', '>').into();
+    let (_, mut marked_ranges) = marked_text_ranges_by(
+        marked_string,
+        vec![complete_from_marker.clone(), replace_range_marker.clone()],
+    );
+
+    let complete_from_position =
+        cx.to_lsp(marked_ranges.remove(&complete_from_marker).unwrap()[0].start);
+    let replace_range =
+        cx.to_lsp_range(marked_ranges.remove(&replace_range_marker).unwrap()[0].clone());
+
+    let mut request = cx.handle_request::<lsp::request::Completion, _, _>(move |url, params, _| {
+        let completions = completions.clone();
+        async move {
+            assert_eq!(params.text_document_position.text_document.uri, url.clone());
+            assert_eq!(
+                params.text_document_position.position,
+                complete_from_position
+            );
+            Ok(Some(lsp::CompletionResponse::Array(
+                completions
+                    .iter()
+                    .map(|completion_text| lsp::CompletionItem {
+                        label: completion_text.to_string(),
+                        text_edit: Some(lsp::CompletionTextEdit::Edit(lsp::TextEdit {
+                            range: replace_range,
+                            new_text: completion_text.to_string(),
+                        })),
+                        ..Default::default()
+                    })
+                    .collect(),
+            )))
+        }
+    });
+
+    async move {
+        request.next().await;
+    }
+}
+
+fn handle_resolve_completion_request<'a>(
+    cx: &mut EditorLspTestContext<'a>,
+    edits: Option<Vec<(&'static str, &'static str)>>,
+) -> impl Future<Output = ()> {
+    let edits = edits.map(|edits| {
+        edits
+            .iter()
+            .map(|(marked_string, new_text)| {
+                let (_, marked_ranges) = marked_text_ranges(marked_string, false);
+                let replace_range = cx.to_lsp_range(marked_ranges[0].clone());
+                lsp::TextEdit::new(replace_range, new_text.to_string())
+            })
+            .collect::<Vec<_>>()
+    });
+
+    let mut request =
+        cx.handle_request::<lsp::request::ResolveCompletionItem, _, _>(move |_, _, _| {
+            let edits = edits.clone();
+            async move {
+                Ok(lsp::CompletionItem {
+                    additional_text_edits: edits,
+                    ..Default::default()
+                })
+            }
+        });
+
+    async move {
+        request.next().await;
+    }
+}
+
+fn handle_copilot_completion_request(
+    lsp: &lsp::FakeLanguageServer,
+    completions: Vec<copilot::request::Completion>,
+    completions_cycling: Vec<copilot::request::Completion>,
+) {
+    lsp.handle_request::<copilot::request::GetCompletions, _, _>(move |_params, _cx| {
+        let completions = completions.clone();
+        async move {
+            Ok(copilot::request::GetCompletionsResult {
+                completions: completions.clone(),
+            })
+        }
+    });
+    lsp.handle_request::<copilot::request::GetCompletionsCycling, _, _>(move |_params, _cx| {
+        let completions_cycling = completions_cycling.clone();
+        async move {
+            Ok(copilot::request::GetCompletionsResult {
+                completions: completions_cycling.clone(),
+            })
+        }
+    });
+}