feat: add autoscroll boolean prop (#1160)

* feat: add autoscroll boolean prop

Fixes #449

* refactor: update autoscroll implementation

Closes #1028
Closes #910

* refactor: only call maybeAdjustScroll in the watcher

* docs: upgrade vuepress

tests/unit/Autoscroll.spec.js

@@ -0,0 +1,61 @@
+import { mountDefault } from "../helpers";
+
+describe("Automatic Scrolling", () => {
+  it("should check if the scroll position needs to be adjusted on up arrow keyUp", async () => {
+    //  Given
+    const Select = mountDefault();
+    const spy = jest.spyOn(Select.vm, "maybeAdjustScroll");
+    Select.vm.typeAheadPointer = 1;
+
+    //  When
+    Select.find({ ref: "search" }).trigger("keydown.up");
+    await Select.vm.$nextTick();
+
+    //  Then
+    expect(spy).toHaveBeenCalled();
+  });
+
+  it("should check if the scroll position needs to be adjusted on down arrow keyUp", async () => {
+    //  Given
+    const Select = mountDefault();
+    const spy = jest.spyOn(Select.vm, "maybeAdjustScroll");
+    Select.vm.typeAheadPointer = 1;
+
+    //  When
+    Select.find({ ref: "search" }).trigger("keydown.down");
+    await Select.vm.$nextTick();
+
+    //  Then
+    expect(spy).toHaveBeenCalled();
+  });
+
+  it("should check if the scroll position needs to be adjusted when filtered options changes", async () => {
+    //  Given
+    const Select = mountDefault();
+    const spy = jest.spyOn(Select.vm, "maybeAdjustScroll");
+    Select.vm.typeAheadPointer = 1;
+
+    //  When
+    Select.vm.search = "two";
+    await Select.vm.$nextTick();
+
+    //  Then
+    expect(spy).toHaveBeenCalled();
+  });
+
+  it("should not adjust scroll position when autoscroll is false", async () => {
+    //  Given
+    const Select = mountDefault({
+      autoscroll: false
+    });
+    const spy = jest.spyOn(Select.vm, "maybeAdjustScroll");
+    Select.vm.typeAheadPointer = 1;
+
+    // When
+    Select.vm.search = "two";
+    await Select.vm.$nextTick();
+
+    //  Then
+    expect(spy).toHaveBeenCalledTimes(0);
+  });
+});