From b4ab1d518fc5f81611435b13bf4e8adcdda68065 Mon Sep 17 00:00:00 2001
From: Tymoteusz Czech <2625371+Tymek@users.noreply.github.com>
Date: Fri, 20 Sep 2024 11:53:37 +0200
Subject: [PATCH 1/2] fix: prevent evaluateFlags from throwing an error if
 definitions are not provided

---
 lib/src/evaluateFlags.ts | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/lib/src/evaluateFlags.ts b/lib/src/evaluateFlags.ts
index 3298a0e..027f96f 100644
--- a/lib/src/evaluateFlags.ts
+++ b/lib/src/evaluateFlags.ts
@@ -12,7 +12,17 @@ export const evaluateFlags = (
 ): {
   toggles: IToggle[];
 } => {
-  const engine = new ToggleEngine(definitions);
+  let engine: ToggleEngine;
+  try {
+    engine = new ToggleEngine(definitions);
+  } catch (error) {
+    console.error(
+      "Unleash: Failed to evaluate flags from provided definitions",
+      error
+    );
+    return { toggles: [] };
+  }
+
   const defaultContext: Context = {
     currentTime: new Date(),
     appName:

From f158414a78f8b98b7ebf945c16d10f9d1055309f Mon Sep 17 00:00:00 2001
From: Tymoteusz Czech <2625371+Tymek@users.noreply.github.com>
Date: Fri, 20 Sep 2024 13:43:20 +0200
Subject: [PATCH 2/2] test evaluateFlags error catching

---
 lib/src/evaluateFlags.test.ts | 43 +++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 lib/src/evaluateFlags.test.ts

diff --git a/lib/src/evaluateFlags.test.ts b/lib/src/evaluateFlags.test.ts
new file mode 100644
index 0000000..a3a0278
--- /dev/null
+++ b/lib/src/evaluateFlags.test.ts
@@ -0,0 +1,43 @@
+import { evaluateFlags } from "./evaluateFlags";
+import type { ClientFeaturesResponse } from "unleash-client";
+
+describe("evaluateFlags", () => {
+  it("should return toggles when engine initializes successfully", () => {
+    const definitions: ClientFeaturesResponse = {
+      version: 1,
+      features: [
+        { name: "featureA", enabled: true },
+        { name: "featureB", enabled: false },
+      ],
+    };
+
+    const result = evaluateFlags(definitions, {});
+
+    expect(result).toEqual({
+      toggles: [
+        {
+          name: "featureA",
+          enabled: true,
+          impressionData: false,
+          variant: {
+            enabled: false,
+            feature_enabled: true,
+            name: "disabled",
+          },
+        },
+      ],
+    });
+  });
+
+  it("should return empty toggles when engine initialization fails", () => {
+    const definitions = {
+      message: "Invalid definitions",
+    };
+
+    const result = evaluateFlags(definitions as any, {});
+
+    expect(result).toEqual({
+      toggles: [],
+    });
+  });
+});