From 1885bf5417b8a7d622e818364b19994aef2ef85f Mon Sep 17 00:00:00 2001
From: Neil Kakkar <neilkakkar@gmail.com>
Date: Mon, 25 Sep 2023 17:19:14 +0100
Subject: [PATCH] fix(flags): Safe access flags in decide v2

---
 lib/Client.php           |  6 +++++-
 test/FeatureFlagTest.php | 19 ++++++++++++++++++-
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/lib/Client.php b/lib/Client.php
index abf1e7c..b490864 100644
--- a/lib/Client.php
+++ b/lib/Client.php
@@ -231,7 +231,11 @@ public function getFeatureFlag(
         if (!$flagWasEvaluatedLocally && !$onlyEvaluateLocally) {
             try {
                 $featureFlags = $this->fetchFeatureVariants($distinctId, $groups, $personProperties, $groupProperties);
-                $result = $featureFlags[$key] ?? null;
+                if(array_key_exists($key, $featureFlags)) {
+                    $result = $featureFlags[$key];
+                } else {
+                    $result = null;
+                }
             } catch (Exception $e) {
                 error_log("[PostHog][Client] Unable to get feature variants:" . $e->getMessage());
                 $result = null;
diff --git a/test/FeatureFlagTest.php b/test/FeatureFlagTest.php
index bdaa60b..3fbb84c 100644
--- a/test/FeatureFlagTest.php
+++ b/test/FeatureFlagTest.php
@@ -11,7 +11,7 @@
 use PostHog\InconclusiveMatchException;
 use PostHog\SizeLimitedHash;
 
-class FeatureFlagMatch extends TestCase
+class FeatureFlagTest extends TestCase
 {
     const FAKE_API_KEY = "random_key";
 
@@ -516,6 +516,23 @@ public function testFlagFallbackToDecide()
         $this->assertEquals(PostHog::getFeatureFlag('feature-2', 'some-distinct'), 'decide-fallback-value');
     }
 
+    public function testFlagFallbackToDecideWithFalseFlag()
+    {
+        $this->http_client = new MockedHttpClient(host: "app.posthog.com", flagEndpointResponse: MockedResponses::FALLBACK_TO_DECIDE_REQUEST);
+        $this->client = new Client(
+            self::FAKE_API_KEY,
+            [
+                "debug" => true,
+            ],
+            $this->http_client,
+            "test"
+        );
+        PostHog::init(null, null, $this->client);
+
+        $this->assertEquals(PostHog::getFeatureFlag('unknown-flag???', 'some-distinct'), null);
+        $this->assertEquals(PostHog::getFeatureFlag('false-flag', 'some-distinct'), null);
+    }
+
     public function testFeatureFlagDefaultsComeIntoPlayOnlyWhenDecideErrorsOut()
     {
         $this->client = new Client(