Address implicit null declaration

Author: sivaram7

src/Test/Unit/Config/Stage/DeployTest.php

@@ -59,7 +59,7 @@ protected function setUp(): void
      *
      * @throws ConfigException
      */
-    public function testGet(string $name, $expectedValue, array $mergedConfig, array $schema = null): void
+    public function testGet(string $name, $expectedValue, array $mergedConfig, array | null $schema = null): void
     {
         $this->mergedConfigMock->expects($this->once())
             ->method('get')

src/Test/Unit/Config/Validator/Deploy/MagentoCloudVariablesTest.php

@@ -59,7 +59,7 @@ protected function setUp(): void
     public function testValidate(
         array $magentoCloudVariables,
         string $expectedResultType,
-        string $suggestionMessage = null
+        string | null $suggestionMessage = null
     ): void {
         $this->environmentMock->expects($this->once())
             ->method('getVariables')

src/Test/Unit/Config/Validator/Deploy/SessionCredentialsTest.php

@@ -58,7 +58,7 @@ protected function setUp(): void
     public function testValidate(
         array $sessionConfig,
         string $expectedResultType,
-        string $expectedErrorMessage = null
+        string | null $expectedErrorMessage = null
     ): void {
         $this->sessionConfigMock->expects($this->once())
             ->method('get')

src/Test/Unit/Step/ValidateConfigurationTest.php

@@ -278,7 +278,7 @@ public function testExecuteTypeStringLevel(): void
      * @return MockObject|ValidatorInterface
      * @throws \ReflectionException
      */
-    private function createValidatorWithError(string $error, string $suggestion, int $errorCode = null): MockObject
+    private function createValidatorWithError(string $error, string $suggestion, int | null $errorCode = null): MockObject
     {
         $warningValidator = $this->getMockForAbstractClass(ValidatorInterface::class);
         $warningResultMock = $this->createMock(Result\Error::class);