Add tool ranker fallback policy tests

test/tool-ranker-fallback.test.mjs

@@ -0,0 +1,46 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+const {ToolRankerFallbackPolicy} = await import("../dist/common/policies.js");
+const {resolveToolRankerFallbackSelection} = await import("../dist/ai/tool-ranker-fallback.js");
+
+const availableToolNames = ["read_file", "search_files"];
+
+test("tool ranker fallback returns no tools when policy is NO_TOOLS", () => {
+    assert.deepEqual(
+        resolveToolRankerFallbackSelection({
+            fallbackPolicy: ToolRankerFallbackPolicy.NO_TOOLS,
+            availableToolNames,
+        }),
+        {
+            toolNames: [],
+            usedRanker: false,
+        },
+    );
+});
+
+test("tool ranker fallback returns all tools when policy is ALL_TOOLS", () => {
+    assert.deepEqual(
+        resolveToolRankerFallbackSelection({
+            fallbackPolicy: ToolRankerFallbackPolicy.ALL_TOOLS,
+            availableToolNames,
+        }),
+        {
+            toolNames: ["read_file", "search_files"],
+            usedRanker: false,
+        },
+    );
+});
+
+test("tool ranker fallback keeps all tools when policy is MAIN_MODEL", () => {
+    assert.deepEqual(
+        resolveToolRankerFallbackSelection({
+            fallbackPolicy: ToolRankerFallbackPolicy.MAIN_MODEL,
+            availableToolNames,
+        }),
+        {
+            toolNames: ["read_file", "search_files"],
+            usedRanker: false,
+        },
+    );
+});