2 files changed, 96 insertions, 2 deletions
diff --git a/src/simulation/actions.js b/src/simulation/actions.js
index 40545c5..a925867 100644
--- a/src/simulation/actions.js
+++ b/src/simulation/actions.js
@@ -22,7 +22,47 @@ const move_forward = {
   },
 };
 
+const move_backward = {
+  size: 1,
+  propose: (agent, head) => {
+    if (head[0] > threshold) {
+      const dx = { n: 0, e: 1, s: 0, w: -1 }[agent.flags.orientation];
+      const dy = { n: -1, e: 0, s: 1, w: 0 }[agent.flags.orientation];
+      return [{
+        agent_changes: [{
+          agent_id: agent.id,
+          x: agent.x - dx,
+          y: agent.y - dy,
+        }],
+      }];
+    } else {
+      return [];
+    }
+  },
+};
+
+
+const turn_left = {
+  size: 1,
+  propose: (agent, head) => {
+    if (head[0] > threshold) {
+      const orientation = { n: 'w', e: 'n', s: 'e', w: 's' }[agent.flags.orientation];
+      return [{
+        agent_changes: [{
+          agent_id: agent.id,
+          flags: { orientation },
+        }],
+      }];
+    } else {
+      return [];
+    }
+  },
+};
+
+
+
+
 
 export const actions = [
-  move_forward,
+  move_forward, move_backward, turn_left,
 ];
diff --git a/src/simulation/actions.test.js b/src/simulation/actions.test.js
index a870352..457015d 100644
--- a/src/simulation/actions.test.js
+++ b/src/simulation/actions.test.js
@@ -3,7 +3,7 @@
 import { actions } from './actions.js';
 
 
-const [move_forward, ...rest] = actions;
+const [move_forward, move_backward, turn_left, ...rest] = actions;
 
 
 test("move forward", () => {
@@ -30,3 +30,57 @@ test("move forward", () => {
   expect(move_forward.propose(e, [0])).toEqual([]);
   expect(move_forward.propose(w, [-1])).toEqual([]);
 });
+
+
+test("move backward", () => {
+  const n = { id: 0, x: 0, y: 0, flags: { orientation: 'n' } };
+  const s = { id: 0, x: 0, y: 0, flags: { orientation: 's' } };
+  const e = { id: 0, x: 0, y: 0, flags: { orientation: 'e' } };
+  const w = { id: 0, x: 0, y: 0, flags: { orientation: 'w' } };
+
+  expect(move_backward.propose(n, [1])).toEqual([
+    { agent_changes: [{ agent_id: 0, x: 0, y: 1 }] },
+  ]);
+  expect(move_backward.propose(s, [1])).toEqual([
+    { agent_changes: [{ agent_id: 0, x: 0, y: -1 }] },
+  ]);
+  expect(move_backward.propose(e, [1])).toEqual([
+    { agent_changes: [{ agent_id: 0, x: -1, y: 0 }] },
+  ]);
+  expect(move_backward.propose(w, [1])).toEqual([
+    { agent_changes: [{ agent_id: 0, x: 1, y: 0 }] },
+  ]);
+
+  expect(move_backward.propose(n, [0])).toEqual([]);
+  expect(move_backward.propose(s, [-1])).toEqual([]);
+  expect(move_backward.propose(e, [0])).toEqual([]);
+  expect(move_backward.propose(w, [-1])).toEqual([]);
+});
+
+
+test("turn_left", () => {
+  const n = { id: 0, x: 0, y: 0, flags: { orientation: 'n' } };
+  const s = { id: 0, x: 0, y: 0, flags: { orientation: 's' } };
+  const e = { id: 0, x: 0, y: 0, flags: { orientation: 'e' } };
+  const w = { id: 0, x: 0, y: 0, flags: { orientation: 'w' } };
+
+  expect(turn_left.propose(n, [1])).toEqual([
+    { agent_changes: [{ agent_id: 0, flags: { orientation: 'w' } }] },
+  ]);
+  expect(turn_left.propose(s, [1])).toEqual([
+    { agent_changes: [{ agent_id: 0, flags: { orientation: 'e' } }] },
+  ]);
+  expect(turn_left.propose(e, [1])).toEqual([
+    { agent_changes: [{ agent_id: 0, flags: { orientation: 'n' } }] },
+  ]);
+  expect(turn_left.propose(w, [1])).toEqual([
+    { agent_changes: [{ agent_id: 0, flags: { orientation: 's' } }] },
+  ]);
+
+  expect(turn_left.propose(n, [0])).toEqual([]);
+  expect(turn_left.propose(s, [-1])).toEqual([]);
+  expect(turn_left.propose(e, [0])).toEqual([]);
+  expect(turn_left.propose(w, [-1])).toEqual([]);
+});
+
+