[spec] Add GestureDetector stub (#4614)

Cf. #4613.

spec/unit/gesturedetector_spec.lua

@@ -0,0 +1,50 @@
+describe("gesturedetector module", function()
+    local GestureDetector
+    setup(function()
+        require("commonrequire")
+        GestureDetector = require("device/gesturedetector")
+    end)
+
+    describe("adjustGesCoordinate", function()
+        local function adjustTest(ges_type, direction, rotation_mode)
+            local ges = {
+                ges = ges_type,
+                direction = direction,
+                multiswipe_directions = direction,
+            }
+            GestureDetector.screen = {}
+            GestureDetector.screen.cur_rotation_mode = rotation_mode
+
+            return GestureDetector:adjustGesCoordinate(ges).direction
+        end
+
+        it("should not translate rotation 0", function()
+            assert.are.equal("north", adjustTest("swipe", "north", 0))
+            assert.are.equal("north", adjustTest("multiswipe", "north", 0))
+            assert.are.equal("north", adjustTest("pan", "north", 0))
+            assert.are.equal("north", adjustTest("two_finger_swipe", "north", 0))
+            assert.are.equal("north", adjustTest("two_finger_pan", "north", 0))
+        end)
+        it("should translate rotation 90", function()
+            assert.are.equal("west", adjustTest("swipe", "north", 3))
+            assert.are.equal("west", adjustTest("multiswipe", "north", 3))
+            assert.are.equal("west", adjustTest("pan", "north", 3))
+            assert.are.equal("west", adjustTest("two_finger_swipe", "north", 3))
+            assert.are.equal("west", adjustTest("two_finger_pan", "north", 3))
+        end)
+        it("should translate rotation 180", function()
+            assert.are.equal("south", adjustTest("swipe", "north", 2))
+            assert.are.equal("south", adjustTest("multiswipe", "north", 2))
+            assert.are.equal("south", adjustTest("pan", "north", 2))
+            assert.are.equal("south", adjustTest("two_finger_swipe", "north", 2))
+            assert.are.equal("south", adjustTest("two_finger_pan", "north", 2))
+        end)
+        it("should translate rotation 270", function()
+            assert.are.equal("east", adjustTest("swipe", "north", 1))
+            assert.are.equal("east", adjustTest("multiswipe", "north", 1))
+            assert.are.equal("east", adjustTest("pan", "north", 1))
+            assert.are.equal("east", adjustTest("two_finger_swipe", "north", 1))
+            assert.are.equal("east", adjustTest("two_finger_pan", "north", 1))
+        end)
+    end)
+end)