Add further scrollback option for longer terminal history

CommandNotch/CommandNotchTests/TerminalScrollCoordinatorTests.swift

@@ -0,0 +1,46 @@
+import XCTest
+@testable import CommandNotch
+
+final class TerminalScrollCoordinatorTests: XCTestCase {
+    func testScrollAwayFromBottomDisablesOutputFollow() {
+        let coordinator = TerminalScrollCoordinator()
+
+        coordinator.terminalDidScroll(to: 0.42, canScroll: true)
+
+        XCTAssertFalse(coordinator.followsOutput)
+        XCTAssertEqual(coordinator.outputRestorePosition(canScroll: true) ?? .nan, 0.42, accuracy: 0.0001)
+    }
+
+    func testTypingReEnablesFollowAndRequestsJumpToBottom() {
+        let coordinator = TerminalScrollCoordinator()
+        coordinator.terminalDidScroll(to: 0.42, canScroll: true)
+
+        let shouldJump = coordinator.userDidStartTyping()
+
+        XCTAssertTrue(shouldJump)
+        XCTAssertTrue(coordinator.followsOutput)
+        XCTAssertNil(coordinator.outputRestorePosition(canScroll: true))
+    }
+
+    func testScrollingBackToBottomReEnablesOutputFollow() {
+        let coordinator = TerminalScrollCoordinator()
+        coordinator.terminalDidScroll(to: 0.42, canScroll: true)
+
+        coordinator.terminalDidScroll(to: 1, canScroll: true)
+
+        XCTAssertTrue(coordinator.followsOutput)
+        XCTAssertNil(coordinator.outputRestorePosition(canScroll: true))
+    }
+
+    func testSuppressedTrackingIgnoresProgrammaticScrollUpdates() {
+        let coordinator = TerminalScrollCoordinator()
+        coordinator.terminalDidScroll(to: 0.42, canScroll: true)
+
+        coordinator.suppressTracking {
+            coordinator.terminalDidScroll(to: 1, canScroll: true)
+        }
+
+        XCTAssertFalse(coordinator.followsOutput)
+        XCTAssertEqual(coordinator.outputRestorePosition(canScroll: true) ?? .nan, 0.42, accuracy: 0.0001)
+    }
+}