diff --git a/Core/tests/Unit/ClientTraitTest.php b/Core/tests/Unit/ClientTraitTest.php
index 5d9a28ef2a55..44dbe398e4cd 100644
--- a/Core/tests/Unit/ClientTraitTest.php
+++ b/Core/tests/Unit/ClientTraitTest.php
@@ -168,10 +168,7 @@ public function testConfigureAuthenticationWithKeyFilePath()
 
     public function testIgnoreKeyFileWhenUsingCredentialsFetcher()
     {
-        $keyFilePath = Fixtures::SERVICE_ACCOUNT_FIXTURE();
-        $key = json_decode(file_get_contents($keyFilePath), true);
-        $key['private_key'] = 'xxx';
-
+        $key = Fixtures::SERVICE_ACCOUNT_FIXTURE();
         $credentials = new ServiceAccountCredentials([], $key);
 
         $conf = $this->impl->call('configureAuthentication', [[
@@ -183,10 +180,7 @@ public function testIgnoreKeyFileWhenUsingCredentialsFetcher()
 
     public function testGetProjectIdFromCredentialsFetcher()
     {
-        $keyFilePath = Fixtures::SERVICE_ACCOUNT_FIXTURE();
-        $key = json_decode(file_get_contents($keyFilePath), true);
-        $key['private_key'] = 'xxx';
-
+        $key = Fixtures::SERVICE_ACCOUNT_FIXTURE();
         $credentials = new ServiceAccountCredentials([], $key);
 
         $this->impl->call('configureAuthentication', [[
diff --git a/Core/tests/Unit/Fixtures.php b/Core/tests/Unit/Fixtures.php
index 663090c8b358..3c45ee6c15c4 100644
--- a/Core/tests/Unit/Fixtures.php
+++ b/Core/tests/Unit/Fixtures.php
@@ -25,9 +25,20 @@ public static function JSON_KEY_FIXTURE()
         return __DIR__ . '/fixtures/json-key-fixture.json';
     }
 
-    public static function SERVICE_ACCOUNT_FIXTURE()
+    public static function SERVICE_ACCOUNT_FIXTURE(): array
     {
-        return __DIR__ . '/fixtures/service-account-fixture.json';
+        return [
+            'type' => 'service_account',
+            'project_id' => 'example-project-12345',
+            'private_key_id' => 'xyz',
+            'client_email' => 'test-service-account@example-project-12345.iam.gserviceaccount.com',
+            'client_id' => '123456789012345678901',
+            'private_key' => 'xyz',
+            'auth_uri' => 'https://accounts.google.com/o/oauth2/auth',
+            'token_uri' => 'https://oauth2.googleapis.com/token',
+            'auth_provider_x509_cert_url' => 'https://www.googleapis.com/oauth2/v1/certs',
+            'client_x509_cert_url' => 'https://www.googleapis.com/robot/v1/metadata/x509/test-service-account%40example-project-12345.iam.gserviceaccount.com'
+        ];
     }
 
     public static function SERVICE_FIXTURE()
diff --git a/Core/tests/Unit/fixtures/service-account-fixture.json b/Core/tests/Unit/fixtures/service-account-fixture.json
deleted file mode 100644
index 8d124ca8ac6a..000000000000
--- a/Core/tests/Unit/fixtures/service-account-fixture.json
+++ /dev/null
@@ -1,11 +0,0 @@
-{
-  "type": "service_account",
-  "project_id": "example-project-12345",
-  "private_key_id": "1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b",
-  "client_email": "test-service-account@example-project-12345.iam.gserviceaccount.com",
-  "client_id": "123456789012345678901",
-  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
-  "token_uri": "https://oauth2.googleapis.com/token",
-  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
-  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/test-service-account%40example-project-12345.iam.gserviceaccount.com"
-}