diff --git a/.github/workflows/bigtable-emulator-system-tests.yaml b/.github/workflows/bigtable-emulator-system-tests.yaml
index c869251b1744..382b797db7e4 100644
--- a/.github/workflows/bigtable-emulator-system-tests.yaml
+++ b/.github/workflows/bigtable-emulator-system-tests.yaml
@@ -26,7 +26,9 @@ jobs:
 
       - name: Install dependencies
         run: |
-          composer update --prefer-dist --no-interaction --no-suggest -d Bigtable/
+          composer config minimum-stability dev -d Bigtable/
+          composer config repositories.local path "../Core" -d Bigtable
+          composer require "google/cloud-core:*" -d Bigtable/
 
       - name: Run system tests
         run: |
diff --git a/.github/workflows/firestore-emulator-system-tests.yaml b/.github/workflows/firestore-emulator-system-tests.yaml
index e0903c9e3cdf..7a758c66fdad 100644
--- a/.github/workflows/firestore-emulator-system-tests.yaml
+++ b/.github/workflows/firestore-emulator-system-tests.yaml
@@ -26,7 +26,9 @@ jobs:
 
       - name: Install dependencies
         run: |
-          composer update --prefer-dist --no-interaction --no-suggest -d Firestore/
+          composer config minimum-stability dev -d Firestore/
+          composer config repositories.local path "../Core" -d Firestore
+          composer require "google/cloud-core:*" -d Firestore/
 
       - name: Run system tests
         run: |
diff --git a/Datastore/tests/System/DatastoreTestCase.php b/Datastore/tests/System/DatastoreTestCase.php
index 52daf4ea9384..ce9bfb91950e 100644
--- a/Datastore/tests/System/DatastoreTestCase.php
+++ b/Datastore/tests/System/DatastoreTestCase.php
@@ -80,7 +80,7 @@ public static function tearDownFixtures()
 
     public function clientProvider()
     {
-        self::setupBeforeClass();
+        self::set_up_before_class();
 
         return [
             'restClient' => [self::$restClient],
diff --git a/Firestore/tests/System/QueryTest.php b/Firestore/tests/System/QueryTest.php
index b3fd5886bcb9..60a2e3083470 100644
--- a/Firestore/tests/System/QueryTest.php
+++ b/Firestore/tests/System/QueryTest.php
@@ -18,7 +18,6 @@
 namespace Google\Cloud\Firestore\Tests\System;
 
 use Google\Cloud\Firestore\FieldPath;
-use Yoast\PHPUnitPolyfills\Polyfills\AssertStringContains;
 
 /**
  * @group firestore
@@ -26,8 +25,6 @@
  */
 class QueryTest extends FirestoreTestCase
 {
-    use AssertStringContains;
-
     private $query;
 
     public function set_up()
@@ -127,8 +124,8 @@ public function testWhereInArray()
         $doc_ids = array_map(function ($doc) {
             return $doc->id();
         }, $docs);
-        $this->assertStringContainsString($doc1->id(), $doc_ids);
-        $this->assertStringContainsString($doc2->id(), $doc_ids);
+        $this->assertContains($doc1->id(), $doc_ids);
+        $this->assertContains($doc2->id(), $doc_ids);
     }
 
     public function testSnapshotCursors()
diff --git a/Spanner/tests/System/BatchTest.php b/Spanner/tests/System/BatchTest.php
index 4554cdb2ac51..7f5438805fc0 100644
--- a/Spanner/tests/System/BatchTest.php
+++ b/Spanner/tests/System/BatchTest.php
@@ -32,7 +32,7 @@ class BatchTest extends SpannerTestCase
 
     public static function set_up_before_class()
     {
-        parent::setupBeforeClass();
+        parent::set_up_before_class();
 
         self::$tableName = uniqid(self::TESTING_PREFIX);
 
diff --git a/Spanner/tests/System/LargeReadTest.php b/Spanner/tests/System/LargeReadTest.php
index e9dd2f83b687..6e81548ce74e 100644
--- a/Spanner/tests/System/LargeReadTest.php
+++ b/Spanner/tests/System/LargeReadTest.php
@@ -40,7 +40,7 @@ class LargeReadTest extends SpannerTestCase
 
     public static function set_up_before_class()
     {
-        parent::setupBeforeClass();
+        parent::set_up_before_class();
 
         self::$tableName = uniqid(self::TESTING_PREFIX);
 
diff --git a/Spanner/tests/System/PgQueryTest.php b/Spanner/tests/System/PgQueryTest.php
index 99123e427f9a..01d5d05ede38 100644
--- a/Spanner/tests/System/PgQueryTest.php
+++ b/Spanner/tests/System/PgQueryTest.php
@@ -41,7 +41,7 @@ class PgQueryTest extends SpannerPgTestCase
 
     public static $timestampVal;
 
-    public static function setUpBeforeClass()
+    public static function set_up_before_class()
     {
         parent::set_up_before_class();
 
diff --git a/Spanner/tests/System/PgReadTest.php b/Spanner/tests/System/PgReadTest.php
index ac9a40ab27f6..ce9855f7d84f 100644
--- a/Spanner/tests/System/PgReadTest.php
+++ b/Spanner/tests/System/PgReadTest.php
@@ -37,9 +37,9 @@ class PgReadTest extends SpannerPgTestCase
     private static $indexes = [];
     private static $dataset;
 
-    public static function setupBeforeClass()
+    public static function set_up_before_class()
     {
-        parent::setupBeforeClass();
+        parent::set_up_before_class();
 
         self::$readTableName = "read_table";
         self::$rangeTableName = "range_table";
diff --git a/Spanner/tests/System/PgTransactionTest.php b/Spanner/tests/System/PgTransactionTest.php
index d824098c6c7a..bf3f19c9cb05 100644
--- a/Spanner/tests/System/PgTransactionTest.php
+++ b/Spanner/tests/System/PgTransactionTest.php
@@ -33,7 +33,7 @@ class PgTransactionTest extends SpannerPgTestCase
     private static $tableName;
     private static $table2;
 
-    public static function setUpBeforeClass()
+    public static function set_up_before_class()
     {
         parent::set_up_before_class();
 
diff --git a/Spanner/tests/System/PgWriteTest.php b/Spanner/tests/System/PgWriteTest.php
index 42eaebf7e0c7..23b04923ab2b 100644
--- a/Spanner/tests/System/PgWriteTest.php
+++ b/Spanner/tests/System/PgWriteTest.php
@@ -40,7 +40,7 @@ class PgWriteTest extends SpannerPgTestCase
     const TABLE_NAME = 'Writes';
     const COMMIT_TIMESTAMP_TABLE_NAME = 'CommitTimestamps';
 
-    public static function setupBeforeClass()
+    public static function set_up_before_class()
     {
         parent::set_up_before_class();
 
diff --git a/Spanner/tests/System/SpannerPgTestCase.php b/Spanner/tests/System/SpannerPgTestCase.php
index a80af2a4f09a..bcc48a3a1791 100644
--- a/Spanner/tests/System/SpannerPgTestCase.php
+++ b/Spanner/tests/System/SpannerPgTestCase.php
@@ -42,7 +42,7 @@ class SpannerPgTestCase extends SystemTestCase
 
     private static $hasSetUp = false;
 
-    public static function setUpBeforeClass()
+    public static function set_up_before_class()
     {
         if (self::$hasSetUp) {
             return;