Merge branch 'eb/sc-139580/empty-flags-state-json' into contract-tests

Author: eli-darkly

src/LaunchDarkly/FeatureFlagsState.php

@@ -149,13 +149,17 @@ public function toValuesMap(): array
     public function jsonSerialize(): array
     {
         $ret = array_replace([], $this->_flagValues);
-        $metaMap = [];
-        foreach ($this->_flagMetadata as $key => $meta) {
-            $meta = array_replace([], $meta);
-            if (isset($meta['reason'])) {
-                $meta['reason'] = $meta['reason']->jsonSerialize();
+        if (count($this->_flagMetadata) === 0) {
+            $metaMap = new \stdClass(); // using object rather than array ensures the JSON value is {}, not []
+        } else {
+            $metaMap = [];
+            foreach ($this->_flagMetadata as $key => $meta) {
+                $meta = array_replace([], $meta);
+                if (isset($meta['reason'])) {
+                    $meta['reason'] = $meta['reason']->jsonSerialize();
+                }
+                $metaMap[$key] = $meta;
             }
-            $metaMap[$key] = $meta;
         }
         $ret['$flagsState'] = $metaMap;
         $ret['$valid'] = $this->_valid;

tests/FeatureFlagsStateTest.php

@@ -138,4 +138,20 @@ public function testJsonEncodeUsesCustomSerializer()
         $decoded = json_decode($json, true);
         $this->assertEquals($expected, $decoded);
     }
+
+    public function testJsonEncodeWithEmptyData()
+    {
+        $state = new FeatureFlagsState(true);
+        $json = json_encode($state);
+
+        $expected = [
+            '$valid' => true,
+            '$flagsState' => []
+        ];
+        $this->assertEquals($expected, json_decode($json, true));
+
+        // Due to ambiguity of PHP array types, we need to verify that the $flagsState value
+        // is an empty JSON object, not an empty JSON array.
+        $this->assertStringContainsString('"$flagsState":{}', $json);
+    }
 }