Unit test to help verify updateFindControlState

Do a simple find and check the params pass to `updatefindcontrolstate` is in
expected shape.

test/unit/pdf_find_controller_spec.js

@@ -1022,4 +1022,35 @@ describe("pdf_find_controller", function () {
       pageMatchesLength: [[1, 1, 1, 1, 1, 1, 1, 1, 1]],
     });
   });
+
+  it("dispatches updateFindControlState with picked state properties", async function () {
+    const testOnFind = ({ eventBus }) =>
+      new Promise(function (resolve) {
+        const eventState = {
+          source: this,
+          type: "",
+          query: "Foo",
+          caseSensitive: true,
+          entireWord: true,
+          findPrevious: false,
+          matchDiacritics: false,
+        };
+        eventBus.dispatch("find", eventState);
+
+        eventBus.on(
+          "updatefindcontrolstate",
+          function onUpdatefindcontrolstate(evt) {
+            expect(evt.state).toBe(FindState.NOT_FOUND);
+            expect(evt.previous).toBe(false);
+            expect(evt.entireWord).toBe(true);
+            expect(evt.matchesCount).toEqual({ current: 0, total: 0 });
+            expect(evt.rawQuery).toBe("Foo");
+            resolve();
+          }
+        );
+      });
+
+    const { eventBus } = await initPdfFindController();
+    await testOnFind({ eventBus });
+  });
 });