it: test natural scrolling

src/it/test_utils/test_container_node_ext.rs

@@ -0,0 +1,20 @@
+use {
+    crate::{
+        it::test_error::TestResult,
+        tree::{ContainerNode, ToplevelNode},
+    },
+    std::rc::Rc,
+};
+
+pub trait TestContainerExt {
+    fn first_toplevel(&self) -> TestResult<Rc<dyn ToplevelNode>>;
+}
+
+impl TestContainerExt for ContainerNode {
+    fn first_toplevel(&self) -> TestResult<Rc<dyn ToplevelNode>> {
+        match self.children.first() {
+            None => bail!("container does not have children"),
+            Some(c) => Ok(c.node.clone()),
+        }
+    }
+}

src/it/test_utils/test_ouput_node_ext.rs

@@ -0,0 +1,20 @@
+use {
+    crate::{
+        it::test_error::TestResult,
+        tree::{OutputNode, WorkspaceNode},
+    },
+    std::rc::Rc,
+};
+
+pub trait TestOutputNodeExt {
+    fn workspace(&self) -> TestResult<Rc<WorkspaceNode>>;
+}
+
+impl TestOutputNodeExt for OutputNode {
+    fn workspace(&self) -> TestResult<Rc<WorkspaceNode>> {
+        match self.workspace.get() {
+            None => bail!("Output node does not have a container"),
+            Some(w) => Ok(w),
+        }
+    }
+}

src/it/test_utils/test_toplevel_node_ext.rs

@@ -0,0 +1,12 @@
+use crate::tree::ToplevelNode;
+
+pub trait TestToplevelNodeExt {
+    fn center(&self) -> (i32, i32);
+}
+
+impl TestToplevelNodeExt for dyn ToplevelNode {
+    fn center(&self) -> (i32, i32) {
+        let rect = self.node_absolute_position();
+        ((rect.x1() + rect.x2()) / 2, (rect.y1() + rect.y2()) / 2)
+    }
+}

src/it/test_utils/test_workspace_node_ext.rs

@@ -0,0 +1,20 @@
+use {
+    crate::{
+        it::test_error::TestResult,
+        tree::{ContainerNode, WorkspaceNode},
+    },
+    std::rc::Rc,
+};
+
+pub trait TestWorkspaceNodeExt {
+    fn container(&self) -> TestResult<Rc<ContainerNode>>;
+}
+
+impl TestWorkspaceNodeExt for WorkspaceNode {
+    fn container(&self) -> TestResult<Rc<ContainerNode>> {
+        match self.container.get() {
+            None => bail!("workspace does not have a container"),
+            Some(c) => Ok(c),
+        }
+    }
+}