diff --git a/.github/workflows/continuous-integration.yml b/.github/workflows/continuous-integration.yml
index e04c197d..30938d14 100644
--- a/.github/workflows/continuous-integration.yml
+++ b/.github/workflows/continuous-integration.yml
@@ -27,20 +27,14 @@ jobs:
 
   lint:
     name: "Lint"
-    needs: ["coding-standards", "coverage"]
     runs-on: "ubuntu-latest"
-    strategy:
-      fail-fast: true
-      matrix:
-        php-version: [ '8.1', '8.2', '8.3', '8.4' ]
     steps:
       - uses: "actions/checkout@v4"
       - uses: "shivammathur/setup-php@v2"
         with:
-          php-version: "${{ matrix.php-version }}"
+          php-version: "latest"
           coverage: "none"
-          ini-values: "memory_limit=-1, zend.assertions=1, error_reporting=-1, display_errors=On"
-          tools: "composer:v2"
+          tools: "composer"
       - uses: "ramsey/composer-install@v3"
       - name: "Lint the PHP source code"
         run: "./vendor/bin/parallel-lint src test"
@@ -60,19 +54,33 @@ jobs:
       - name: "Check coding standards"
         run: "./vendor/bin/phpcs"
 
+  static-analysis:
+    name: "Static Analysis"
+    runs-on: "ubuntu-latest"
+    steps:
+      - uses: "actions/checkout@v4"
+      - uses: "shivammathur/setup-php@v2"
+        with:
+          php-version: "latest"
+          coverage: "none"
+          ini-values: "memory_limit=-1"
+          tools: "composer"
+      - uses: "ramsey/composer-install@v3"
+      - name: "Analyze code for errors"
+        run: "./vendor/bin/phpstan"
+
   coverage:
     name: "Coverage"
+    needs: ["coding-standards", "lint", "static-analysis"]
     runs-on: "ubuntu-latest"
     steps:
       - uses: "actions/checkout@v4"
       - uses: "shivammathur/setup-php@v2"
         with:
           php-version: "latest"
-          coverage: "pcov"
+          coverage: "xdebug"
           ini-values: "memory_limit=-1, zend.assertions=1, error_reporting=-1, display_errors=On"
           tools: "composer"
-      - name: "Prepare for tests"
-        run: "mkdir -p build/logs"
       - uses: "ramsey/composer-install@v3"
       - name: "Run unit tests"
         run: "./vendor/bin/phpunit --colors=always --coverage-clover build/logs/clover.xml --coverage-text"
@@ -81,7 +89,7 @@ jobs:
 
   unit-tests:
     name: "Unit Tests"
-    needs: ["lint"]
+    needs: ["coverage"]
     runs-on: "ubuntu-latest"
     strategy:
       fail-fast: true
@@ -95,8 +103,6 @@ jobs:
           coverage: "none"
           ini-values: "memory_limit=-1, zend.assertions=1, error_reporting=-1, display_errors=On"
           tools: "composer"
-      - name: "Prepare for tests"
-        run: "mkdir -p build/logs"
       - uses: "ramsey/composer-install@v3"
       - name: "Run unit tests"
         run: "./vendor/bin/phpunit --colors=always --no-coverage"
diff --git a/composer.json b/composer.json
index 177c929b..08a60255 100644
--- a/composer.json
+++ b/composer.json
@@ -37,6 +37,10 @@
         "guzzlehttp/guzzle": "^7.4.5",
         "mockery/mockery": "^1.6",
         "php-parallel-lint/php-parallel-lint": "^1.4",
+        "phpstan/extension-installer": "^1.4",
+        "phpstan/phpstan": "^2.0",
+        "phpstan/phpstan-mockery": "^2.0",
+        "phpstan/phpstan-phpunit": "^2.0",
         "phpunit/phpunit": "^10.5 || ^11.5",
         "ramsey/coding-standard": "^2.2",
         "squizlabs/php_codesniffer": "^3.11"
@@ -54,17 +58,20 @@
     "config": {
         "allow-plugins": {
             "dealerdirect/phpcodesniffer-composer-installer": true,
-            "ergebnis/composer-normalize": true
+            "ergebnis/composer-normalize": true,
+            "phpstan/extension-installer": true
         },
         "sort-packages": true
     },
     "scripts": {
+        "analyze": "phpstan analyze --memory-limit=1G",
         "cs": "phpcs",
         "cs-fix": "phpcbf",
         "lint": "parallel-lint src test",
         "test": [
             "@lint",
             "@cs",
+            "@analyze",
             "phpunit --no-coverage"
         ]
     },
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
new file mode 100644
index 00000000..224dfbcb
--- /dev/null
+++ b/phpstan.neon.dist
@@ -0,0 +1,6 @@
+parameters:
+    level: max
+    treatPhpDocTypesAsCertain: false
+    paths:
+        - src
+        - test
diff --git a/src/Grant/GrantFactory.php b/src/Grant/GrantFactory.php
index 314bce26..7c0cb07d 100644
--- a/src/Grant/GrantFactory.php
+++ b/src/Grant/GrantFactory.php
@@ -19,7 +19,10 @@
 
 use League\OAuth2\Client\Grant\Exception\InvalidGrantException;
 
+use function gettype;
 use function is_object;
+use function is_scalar;
+use function is_string;
 use function is_subclass_of;
 use function sprintf;
 use function str_replace;
@@ -83,9 +86,15 @@ protected function registerDefaultGrant(string $name)
      * Determines if a variable is a valid grant.
      *
      * @return bool
+     *
+     * @phpstan-assert-if-true class-string<AbstractGrant> | AbstractGrant $class
      */
     public function isGrant(mixed $class)
     {
+        if (!is_string($class) && !is_object($class)) {
+            return false;
+        }
+
         return is_subclass_of($class, AbstractGrant::class);
     }
 
@@ -95,14 +104,21 @@ public function isGrant(mixed $class)
      * @return void
      *
      * @throws InvalidGrantException
+     *
+     * @phpstan-assert class-string<AbstractGrant> | AbstractGrant $class
      */
     public function checkGrant(mixed $class)
     {
         if (!$this->isGrant($class)) {
-            throw new InvalidGrantException(sprintf(
-                'Grant "%s" must extend AbstractGrant',
-                is_object($class) ? $class::class : $class,
-            ));
+            if (is_object($class)) {
+                $type = $class::class;
+            } elseif (is_scalar($class)) {
+                $type = $class;
+            } else {
+                $type = gettype($class);
+            }
+
+            throw new InvalidGrantException(sprintf('Grant "%s" must extend AbstractGrant', $type));
         }
     }
 }
diff --git a/src/OptionProvider/HttpBasicAuthOptionProvider.php b/src/OptionProvider/HttpBasicAuthOptionProvider.php
index e4837b37..efe5c1e4 100644
--- a/src/OptionProvider/HttpBasicAuthOptionProvider.php
+++ b/src/OptionProvider/HttpBasicAuthOptionProvider.php
@@ -20,6 +20,7 @@
 use InvalidArgumentException;
 
 use function base64_encode;
+use function is_string;
 use function sprintf;
 
 /**
@@ -30,14 +31,20 @@
 class HttpBasicAuthOptionProvider extends PostAuthOptionProvider
 {
     /**
+     * @return array{headers: array{content-type: string, Authorization: string}, body?: string}
+     *
      * @inheritdoc
      */
-    public function getAccessTokenOptions($method, array $params)
+    public function getAccessTokenOptions(string $method, array $params): array
     {
         if (!isset($params['client_id']) || !isset($params['client_secret'])) {
             throw new InvalidArgumentException('clientId and clientSecret are required for http basic auth');
         }
 
+        if (!is_string($params['client_id']) || !is_string($params['client_secret'])) {
+            throw new InvalidArgumentException('clientId and clientSecret must be string values');
+        }
+
         $encodedCredentials = base64_encode(sprintf('%s:%s', $params['client_id'], $params['client_secret']));
         unset($params['client_id'], $params['client_secret']);
 
diff --git a/src/OptionProvider/PostAuthOptionProvider.php b/src/OptionProvider/PostAuthOptionProvider.php
index 3368dbe1..2afe6f67 100644
--- a/src/OptionProvider/PostAuthOptionProvider.php
+++ b/src/OptionProvider/PostAuthOptionProvider.php
@@ -28,9 +28,11 @@ class PostAuthOptionProvider implements OptionProviderInterface
     use QueryBuilderTrait;
 
     /**
+     * @return array{headers: array{content-type: string}, body?: string}
+     *
      * @inheritdoc
      */
-    public function getAccessTokenOptions($method, array $params)
+    public function getAccessTokenOptions(string $method, array $params): array
     {
         $options = ['headers' => ['content-type' => 'application/x-www-form-urlencoded']];
 
diff --git a/src/Provider/AbstractProvider.php b/src/Provider/AbstractProvider.php
index 62eb41df..9abf7707 100644
--- a/src/Provider/AbstractProvider.php
+++ b/src/Provider/AbstractProvider.php
@@ -39,11 +39,13 @@
 
 use function array_merge;
 use function array_merge_recursive;
+use function assert;
 use function base64_encode;
 use function bin2hex;
 use function hash;
 use function header;
 use function implode;
+use function intdiv;
 use function is_array;
 use function is_string;
 use function json_decode;
@@ -118,10 +120,15 @@ abstract class AbstractProvider
      * @param array<string, mixed> $options An array of options to set on this
      *     provider. Options include `clientId`, `clientSecret`, `redirectUri`,
      *     and `state`. Individual providers may introduce more options, as needed.
-     * @param array<string, mixed> $collaborators An array of collaborators that
-     *     may be used to override this provider's default behavior. Collaborators
-     *     include `grantFactory`, `requestFactory`, and `httpClient`. Individual
-     *     providers may introduce more collaborators, as needed.
+     * @param array{
+     *     grantFactory?: GrantFactory,
+     *     requestFactory?: RequestFactoryInterface,
+     *     streamFactory?: StreamFactoryInterface,
+     *     httpClient?: ClientInterface,
+     *     optionProvider?: OptionProviderInterface,
+     * } $collaborators An array of collaborators that may be used to override
+     *     this provider's default behavior. Individual providers may introduce
+     *     more collaborators, as needed.
      */
     public function __construct(array $options = [], array $collaborators = [])
     {
@@ -355,7 +362,7 @@ abstract public function getResourceOwnerDetailsUrl(AccessToken $token);
      * Returns a new random string to use as the state parameter in an
      * authorization flow.
      *
-     * @param  int $length Length of the random string to be generated.
+     * @param int<1, max> $length Length of the random string to be generated.
      *
      * @return string
      */
@@ -363,7 +370,10 @@ protected function getRandomState(int $length = 32)
     {
         // Converting bytes to hex will always double length. Hence, we can reduce
         // the amount of bytes by half to produce the correct length.
-        return bin2hex(random_bytes($length / 2));
+        $length = intdiv($length, 2);
+        assert($length >= 1);
+
+        return bin2hex(random_bytes($length));
     }
 
     /**
@@ -371,20 +381,14 @@ protected function getRandomState(int $length = 32)
      * hashed as code_challenge parameters in an authorization flow.
      * Must be between 43 and 128 characters long.
      *
-     * @param  int $length Length of the random string to be generated.
+     * @param int<1, max> $length Length of the random string to be generated.
      * @return string
      */
     protected function getRandomPkceCode(int $length = 64)
     {
-        return substr(
-            strtr(
-                base64_encode(random_bytes($length)),
-                '+/',
-                '-_',
-            ),
-            0,
-            $length,
-        );
+        assert($length >= 1);
+
+        return substr(strtr(base64_encode(random_bytes($length)), '+/', '-_'), 0, $length);
     }
 
     /**
@@ -446,6 +450,7 @@ protected function getAuthorizationParameters(array $options)
         }
 
         // Store the state as it may need to be accessed later on.
+        assert(is_string($options['state']));
         $this->state = $options['state'];
 
         $pkceMethod = $this->getPkceMethod();
@@ -570,6 +575,7 @@ protected function getAccessTokenMethod()
      */
     protected function getAccessTokenResourceOwnerId()
     {
+        /** @var string | null */
         return static::ACCESS_TOKEN_RESOURCE_OWNER_ID;
     }
 
@@ -625,7 +631,11 @@ protected function getAccessTokenUrl(array $params)
     /**
      * Returns a prepared request for requesting an access token.
      *
-     * @param array<string, mixed> $params Query string parameters
+     * @param array{
+     *     headers?: array<string, string>,
+     *     version?: string,
+     *     body?: string,
+     * } $params Any of "headers", "body", and "version".
      *
      * @return RequestInterface
      */
@@ -633,6 +643,14 @@ protected function getAccessTokenRequest(array $params)
     {
         $method = $this->getAccessTokenMethod();
         $url = $this->getAccessTokenUrl($params);
+
+        /**
+         * @var array{
+         *     headers?: array<string, string>,
+         *     version?: string,
+         *     body?: string,
+         * } $options
+         */
         $options = $this->optionProvider->getAccessTokenOptions($this->getAccessTokenMethod(), $params);
 
         return $this->getRequest($method, $url, $options);
@@ -672,14 +690,25 @@ public function getAccessToken(mixed $grant, array $options = [])
             $params['code_verifier'] = $this->pkceCode;
         }
 
+        /**
+         * @var array{
+         *     headers?: array<string, string>,
+         *     version?: string,
+         *     body?: string,
+         * } $params
+         */
         $params = $grant->prepareRequestParameters($params, $options);
+
         $request = $this->getAccessTokenRequest($params);
+
+        /** @var array<string, mixed> $response */
         $response = $this->getParsedResponse($request);
         if (is_array($response) === false) {
             throw new UnexpectedValueException(
                 'Invalid response received from Authorization Server. Expected JSON.',
             );
         }
+
         $prepared = $this->prepareAccessTokenResponse($response);
 
         return $this->createAccessToken($prepared, $grant);
@@ -688,7 +717,11 @@ public function getAccessToken(mixed $grant, array $options = [])
     /**
      * Returns a PSR-7 request instance that is not authenticated.
      *
-     * @param array<string, mixed> $options
+     * @param array{
+     *     headers?: array<string, string>,
+     *     version?: string,
+     *     body?: string,
+     * } $options Any of "headers", "body", and "version".
      *
      * @return RequestInterface
      */
@@ -700,7 +733,11 @@ public function getRequest(string $method, string $url, array $options = [])
     /**
      * Returns an authenticated PSR-7 request instance.
      *
-     * @param array<string, mixed> $options Any of "headers", "body", and "protocolVersion".
+     * @param array{
+     *     headers?: array<string, string>,
+     *     version?: string,
+     *     body?: string,
+     * } $options Any of "headers", "body", and "version".
      *
      * @return RequestInterface
      */
@@ -716,7 +753,11 @@ public function getAuthenticatedRequest(
     /**
      * Creates a PSR-7 request instance.
      *
-     * @param array<string, mixed> $options
+     * @param array{
+     *     headers?: array<string, string>,
+     *     version?: string,
+     *     body?: string,
+     * } $options
      *
      * @return RequestInterface
      */
@@ -730,6 +771,13 @@ protected function createRequest(
             'headers' => $this->getHeaders($token),
         ];
 
+        /**
+         * @var array{
+         *     headers: array<string, string>,
+         *     version?: string,
+         *     body?: string,
+         * } $options
+         */
         $options = array_merge_recursive($defaults, $options);
         $requestFactory = $this->getRequestFactory();
         $streamFactory = $this->getStreamFactory();
@@ -780,6 +828,7 @@ public function getParsedResponse(RequestInterface $request)
             $response = $e->getResponse();
         }
 
+        /** @var array<string, mixed> $parsed */
         $parsed = $this->parseResponse($response);
 
         $this->checkResponse($response, $parsed);
@@ -807,6 +856,7 @@ protected function parseJson(string $content)
             ));
         }
 
+        /** @var array<string, mixed> */
         return $content;
     }
 
@@ -937,7 +987,7 @@ public function getResourceOwner(AccessToken $token)
     /**
      * Requests resource owner details.
      *
-     * @return mixed
+     * @return array<string, mixed>
      *
      * @throws ClientExceptionInterface
      * @throws IdentityProviderException
@@ -957,6 +1007,7 @@ protected function fetchResourceOwnerDetails(AccessToken $token)
             );
         }
 
+        /** @var array<string, mixed> */
         return $response;
     }
 
@@ -981,7 +1032,7 @@ protected function getDefaultHeaders()
      * No default is provided, providers must overload this method to activate
      * authorization headers.
      *
-     * @param mixed $token Either a string or an access token instance
+     * @param AccessTokenInterface | string | null $token Either a string or an access token instance
      *
      * @return array<string, mixed>
      */
@@ -995,11 +1046,11 @@ protected function getAuthorizationHeaders(AccessTokenInterface | string | null
      *
      * The request will be authenticated if an access token is provided.
      *
-     * @param mixed $token object or string
+     * @param AccessTokenInterface | string | null $token object or string
      *
      * @return array<string, mixed>
      */
-    public function getHeaders(mixed $token = null)
+    public function getHeaders(AccessTokenInterface | string | null $token = null)
     {
         if ($token) {
             return array_merge(
diff --git a/src/Provider/GenericProvider.php b/src/Provider/GenericProvider.php
index 7c5da40f..dbf6cdab 100644
--- a/src/Provider/GenericProvider.php
+++ b/src/Provider/GenericProvider.php
@@ -18,10 +18,15 @@
 namespace League\OAuth2\Client\Provider;
 
 use InvalidArgumentException;
+use League\OAuth2\Client\Grant\GrantFactory;
+use League\OAuth2\Client\OptionProvider\OptionProviderInterface;
 use League\OAuth2\Client\Provider\Exception\IdentityProviderException;
 use League\OAuth2\Client\Token\AccessToken;
 use League\OAuth2\Client\Tool\BearerAuthorizationTrait;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestFactoryInterface;
 use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\StreamFactoryInterface;
 
 use function array_diff_key;
 use function array_flip;
@@ -50,6 +55,7 @@ class GenericProvider extends AbstractProvider
 
     /**
      * @var list<string> | null
+     * @phpstan-ignore property.unusedType
      */
     private ?array $scopes = null;
 
@@ -57,11 +63,21 @@ class GenericProvider extends AbstractProvider
     private string $responseError = 'error';
     private string $responseCode;
     private string $responseResourceOwnerId = 'id';
+
+    /**
+     * @phpstan-ignore property.unusedType
+     */
     private ?string $pkceMethod = null;
 
     /**
      * @param array<string, mixed> $options
-     * @param array<string, mixed> $collaborators
+     * @param array{
+     *     grantFactory?: GrantFactory,
+     *     requestFactory?: RequestFactoryInterface,
+     *     streamFactory?: StreamFactoryInterface,
+     *     httpClient?: ClientInterface,
+     *     optionProvider?: OptionProviderInterface,
+     * } $collaborators
      */
     public function __construct(array $options = [], array $collaborators = [])
     {
@@ -162,7 +178,7 @@ public function getResourceOwnerDetailsUrl(AccessToken $token)
      */
     public function getDefaultScopes()
     {
-        return $this->scopes;
+        return $this->scopes ?? [];
     }
 
     /**
@@ -207,7 +223,10 @@ protected function checkResponse(ResponseInterface $response, $data)
             if (!is_string($error)) {
                 $error = var_export($error, true);
             }
+
+            /** @var int | string $code */
             $code = isset($this->responseCode) && isset($data[$this->responseCode]) ? $data[$this->responseCode] : 0;
+
             if (!is_int($code)) {
                 $code = intval($code);
             }
diff --git a/src/Token/AccessToken.php b/src/Token/AccessToken.php
index 627c09ad..a706a422 100644
--- a/src/Token/AccessToken.php
+++ b/src/Token/AccessToken.php
@@ -18,11 +18,15 @@
 namespace League\OAuth2\Client\Token;
 
 use InvalidArgumentException;
+use ReturnTypeWillChange;
 use RuntimeException;
 
 use function array_diff_key;
 use function array_flip;
+use function is_int;
 use function is_numeric;
+use function is_scalar;
+use function is_string;
 use function time;
 
 /**
@@ -83,17 +87,20 @@ public function getTimeNow()
      */
     public function __construct(array $options = [])
     {
-        if (!isset($options['access_token'])) {
+        if (!isset($options['access_token']) || !is_string($options['access_token'])) {
             throw new InvalidArgumentException('Required option not passed: "access_token"');
         }
 
         $this->accessToken = $options['access_token'];
 
-        if (isset($options['resource_owner_id'])) {
+        if (
+            isset($options['resource_owner_id'])
+            && (is_string($options['resource_owner_id']) || is_int($options['resource_owner_id']))
+        ) {
             $this->resourceOwnerId = $options['resource_owner_id'];
         }
 
-        if (isset($options['refresh_token'])) {
+        if (isset($options['refresh_token']) && is_string($options['refresh_token'])) {
             $this->refreshToken = $options['refresh_token'];
         }
 
@@ -105,11 +112,11 @@ public function __construct(array $options = [])
                 throw new InvalidArgumentException('expires_in value must be an integer');
             }
 
-            $this->expires = $options['expires_in'] !== 0 ? $this->getTimeNow() + $options['expires_in'] : 0;
+            $this->expires = $options['expires_in'] !== 0 ? $this->getTimeNow() + (int) $options['expires_in'] : 0;
         } elseif (isset($options['expires'])) {
             // Some providers supply the seconds until expiration rather than
             // the exact timestamp. Take a best guess at which we received.
-            $expires = (int) $options['expires'];
+            $expires = is_scalar($options['expires']) ? (int) $options['expires'] : 0;
 
             if (!$this->isExpirationTimestamp($expires)) {
                 $expires += $this->getTimeNow();
@@ -163,7 +170,7 @@ public function getRefreshToken()
     /**
      * @inheritdoc
      */
-    public function setRefreshToken($refreshToken)
+    public function setRefreshToken(string $refreshToken)
     {
         $this->refreshToken = $refreshToken;
     }
@@ -217,6 +224,7 @@ public function __toString()
     /**
      * @inheritdoc
      */
+    #[ReturnTypeWillChange]
     public function jsonSerialize()
     {
         $parameters = $this->values;
diff --git a/src/Token/ResourceOwnerAccessTokenInterface.php b/src/Token/ResourceOwnerAccessTokenInterface.php
index 83324b22..5d217aae 100644
--- a/src/Token/ResourceOwnerAccessTokenInterface.php
+++ b/src/Token/ResourceOwnerAccessTokenInterface.php
@@ -22,7 +22,7 @@ interface ResourceOwnerAccessTokenInterface extends AccessTokenInterface
     /**
      * Returns the resource owner identifier, if defined.
      *
-     * @return string | null
+     * @return int | string | null
      */
     public function getResourceOwnerId();
 }
diff --git a/src/Tool/ArrayAccessorTrait.php b/src/Tool/ArrayAccessorTrait.php
index f3b7c712..46836624 100644
--- a/src/Tool/ArrayAccessorTrait.php
+++ b/src/Tool/ArrayAccessorTrait.php
@@ -38,7 +38,7 @@ trait ArrayAccessorTrait
      */
     private function getValueByKey(array $data, mixed $key, mixed $default = null)
     {
-        if (!is_string($key) || !isset($key) || !count($data)) {
+        if (!is_string($key) || !count($data)) {
             return $default;
         }
 
diff --git a/src/Tool/MacAuthorizationTrait.php b/src/Tool/MacAuthorizationTrait.php
index f2c8f375..14c293c7 100644
--- a/src/Tool/MacAuthorizationTrait.php
+++ b/src/Tool/MacAuthorizationTrait.php
@@ -17,7 +17,6 @@
 
 namespace League\OAuth2\Client\Tool;
 
-use League\OAuth2\Client\Token\AccessToken;
 use League\OAuth2\Client\Token\AccessTokenInterface;
 
 use function compact;
@@ -37,7 +36,7 @@ trait MacAuthorizationTrait
      *
      * @return string
      */
-    abstract protected function getTokenId(AccessToken $token);
+    abstract protected function getTokenId(AccessTokenInterface | string | null $token);
 
     /**
      * Returns the MAC signature for the current request.
diff --git a/src/Tool/ProviderRedirectTrait.php b/src/Tool/ProviderRedirectTrait.php
index 0e10f6c6..0eea8145 100644
--- a/src/Tool/ProviderRedirectTrait.php
+++ b/src/Tool/ProviderRedirectTrait.php
@@ -24,6 +24,7 @@
 use Psr\Http\Client\ClientInterface;
 use Psr\Http\Message\RequestInterface;
 use Psr\Http\Message\ResponseInterface;
+use RuntimeException;
 
 trait ProviderRedirectTrait
 {
@@ -36,10 +37,10 @@ trait ProviderRedirectTrait
      * Retrieves a response for a given request and retrieves subsequent
      * responses, with authorization headers, if a redirect is detected.
      *
-     * @return ResponseInterface
+     * @return ResponseInterface | null
      *
-     * @throws BadResponseException
      * @throws ClientExceptionInterface
+     * @throws RuntimeException
      */
     protected function followRequestRedirects(RequestInterface $request)
     {
@@ -48,9 +49,7 @@ protected function followRequestRedirects(RequestInterface $request)
 
         while ($attempts < $this->redirectLimit) {
             $attempts++;
-            $response = $this->getHttpClient()->send($request, [
-                'allow_redirects' => false,
-            ]);
+            $response = $this->getHttpClient()->sendRequest($request);
 
             if ($this->isRedirect($response)) {
                 $redirectUrl = new Uri($response->getHeader('Location')[0]);
@@ -98,7 +97,7 @@ protected function isRedirect(ResponseInterface $response)
      * WARNING: This method does not attempt to catch exceptions caused by HTTP
      * errors! It is recommended to wrap this method in a try/catch block.
      *
-     * @return ResponseInterface
+     * @return ResponseInterface | null
      *
      * @throws ClientExceptionInterface
      */
diff --git a/src/Tool/RequiredParameterTrait.php b/src/Tool/RequiredParameterTrait.php
index 7ef96661..0c9746fb 100644
--- a/src/Tool/RequiredParameterTrait.php
+++ b/src/Tool/RequiredParameterTrait.php
@@ -18,7 +18,6 @@
 namespace League\OAuth2\Client\Tool;
 
 use BadMethodCallException;
-use InvalidArgumentException;
 
 use function sprintf;
 
@@ -54,7 +53,7 @@ private function checkRequiredParameter(string $name, array $params)
      *
      * @return void
      *
-     * @throws InvalidArgumentException
+     * @throws BadMethodCallException
      */
     private function checkRequiredParameters(array $names, array $params)
     {
diff --git a/test/src/Grant/AuthorizationCodeTest.php b/test/src/Grant/AuthorizationCodeTest.php
index 1fd5e0a4..99bf3889 100644
--- a/test/src/Grant/AuthorizationCodeTest.php
+++ b/test/src/Grant/AuthorizationCodeTest.php
@@ -22,7 +22,7 @@ public static function providerGetAccessToken(): array
 
     protected function getParamExpectation(): Closure
     {
-        return fn ($body) => isset($body['grant_type'])
+        return fn (array $body) => isset($body['grant_type'])
                 && $body['grant_type'] === 'authorization_code'
                 && isset($body['code']);
     }
diff --git a/test/src/Grant/ClientCredentialsTest.php b/test/src/Grant/ClientCredentialsTest.php
index 7cc65399..552b84f8 100644
--- a/test/src/Grant/ClientCredentialsTest.php
+++ b/test/src/Grant/ClientCredentialsTest.php
@@ -21,7 +21,7 @@ public static function providerGetAccessToken(): array
 
     protected function getParamExpectation(): Closure
     {
-        return fn ($body) => isset($body['grant_type'])
+        return fn (array $body) => isset($body['grant_type'])
                 && $body['grant_type'] === 'client_credentials';
     }
 
diff --git a/test/src/Grant/GrantFactoryTest.php b/test/src/Grant/GrantFactoryTest.php
index c959fc43..344a8ae4 100644
--- a/test/src/Grant/GrantFactoryTest.php
+++ b/test/src/Grant/GrantFactoryTest.php
@@ -72,6 +72,8 @@ public function testIsGrant(): void
         $grant = $factory->getGrant('password');
 
         $this->assertTrue($factory->isGrant($grant));
+
+        /** @phpstan-ignore method.impossibleType */
         $this->assertFalse($factory->isGrant('stdClass'));
     }
 
@@ -89,6 +91,8 @@ public function testCheckGrantInvalidFails(): void
         $this->expectException(InvalidGrantException::class);
 
         $factory = new GrantFactory();
+
+        /** @phpstan-ignore method.impossibleType */
         $factory->checkGrant('stdClass');
     }
 }
diff --git a/test/src/Grant/GrantTestCase.php b/test/src/Grant/GrantTestCase.php
index 25b771d7..42d389ab 100644
--- a/test/src/Grant/GrantTestCase.php
+++ b/test/src/Grant/GrantTestCase.php
@@ -14,6 +14,7 @@
 use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\TestCase;
 use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestInterface;
 use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\StreamInterface;
 
@@ -87,7 +88,7 @@ public function testGetAccessToken(string $grant, array $params = []): void
         $client
             ->shouldReceive('sendRequest')
             ->once()
-            ->withArgs(function ($request) {
+            ->withArgs(function (RequestInterface $request) {
                 parse_str((string) $request->getBody(), $body);
 
                 return call_user_func($this->getParamExpectation(), $body);
diff --git a/test/src/Grant/PasswordTest.php b/test/src/Grant/PasswordTest.php
index ee49be4f..93630115 100644
--- a/test/src/Grant/PasswordTest.php
+++ b/test/src/Grant/PasswordTest.php
@@ -22,7 +22,7 @@ public static function providerGetAccessToken(): array
 
     protected function getParamExpectation(): Closure
     {
-        return fn ($body) => isset($body['grant_type'])
+        return fn (array $body) => isset($body['grant_type'])
                 && $body['grant_type'] === 'password'
                 && isset($body['username'])
                 && isset($body['password'])
diff --git a/test/src/Grant/RefreshTokenTest.php b/test/src/Grant/RefreshTokenTest.php
index d4d54b59..eaccbeed 100644
--- a/test/src/Grant/RefreshTokenTest.php
+++ b/test/src/Grant/RefreshTokenTest.php
@@ -22,7 +22,7 @@ public static function providerGetAccessToken(): array
 
     protected function getParamExpectation(): Closure
     {
-        return fn ($body) => isset($body['grant_type'])
+        return fn (array $body) => isset($body['grant_type'])
                 && $body['grant_type'] === 'refresh_token';
     }
 
diff --git a/test/src/OptionProvider/PostAuthOptionProviderTest.php b/test/src/OptionProvider/PostAuthOptionProviderTest.php
index 8eb5857e..799bed99 100644
--- a/test/src/OptionProvider/PostAuthOptionProviderTest.php
+++ b/test/src/OptionProvider/PostAuthOptionProviderTest.php
@@ -24,6 +24,6 @@ public function testGetAccessTokenOptions(): void
         ]);
 
         $this->assertArrayHasKey('headers', $options);
-        $this->assertEquals('client_id=test&client_secret=test', $options['body']);
+        $this->assertEquals('client_id=test&client_secret=test', $options['body'] ?? null);
     }
 }
diff --git a/test/src/Provider/AbstractProviderTest.php b/test/src/Provider/AbstractProviderTest.php
index d191459e..5ea69b01 100644
--- a/test/src/Provider/AbstractProviderTest.php
+++ b/test/src/Provider/AbstractProviderTest.php
@@ -16,8 +16,9 @@
 use League\OAuth2\Client\Provider\Exception\IdentityProviderException;
 use League\OAuth2\Client\Test\Provider\Fake as MockProvider;
 use League\OAuth2\Client\Token\AccessToken;
-use League\OAuth2\Client\Token\AccessTokenInterface;
+use League\OAuth2\Client\Token\ResourceOwnerAccessTokenInterface;
 use Mockery;
+use Mockery\Adapter\Phpunit\MockeryPHPUnitIntegration;
 use Mockery\MockInterface;
 use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\TestCase;
@@ -45,6 +46,8 @@
 
 class AbstractProviderTest extends TestCase
 {
+    use MockeryPHPUnitIntegration;
+
     protected function getMockProvider(): MockProvider
     {
         return new MockProvider([
@@ -215,7 +218,7 @@ public function testSetRedirectHandler(): void
         $testFunction = false;
         $state = false;
 
-        $callback = function ($url, $provider) use (&$testFunction, &$state) {
+        $callback = function (string $url, AbstractProvider $provider) use (&$testFunction, &$state) {
             $testFunction = $url;
             $state = $provider->getState();
         };
@@ -267,6 +270,8 @@ public function testGetUserProperties(?string $name = null, ?string $email = nul
         ]);
 
         $provider->setHttpClient($client);
+
+        /** @var MockProvider\User $user */
         $user = $provider->getResourceOwner($token);
         $url = $provider->getResourceOwnerDetailsUrl($token);
 
@@ -280,7 +285,7 @@ public function testGetUserProperties(?string $name = null, ?string $email = nul
         $client
             ->shouldHaveReceived('sendRequest')
             ->once()
-            ->withArgs(fn ($request) => $request->getMethod() === 'GET'
+            ->withArgs(fn (RequestInterface $request) => $request->getMethod() === 'GET'
                     && $request->hasHeader('Authorization')
                     && (string) $request->getUri() === $url);
     }
@@ -324,7 +329,7 @@ public function testGetUserPropertiesThrowsExceptionWhenNonJsonResponseIsReceive
     }
 
     /**
-     * @return array<string, array{0: string, 1: string, 2: int}>
+     * @return array<string, array{0?: string, 1?: string, 2?: int}>
      */
     public static function userPropertyProvider(): array
     {
@@ -352,14 +357,14 @@ public function testScopesOverloadedDuringAuthorize(): void
 
         $url = $provider->getAuthorizationUrl();
 
-        parse_str(parse_url($url, PHP_URL_QUERY), $qs);
+        parse_str((string) parse_url($url, PHP_URL_QUERY), $qs);
 
         $this->assertArrayHasKey('scope', $qs);
         $this->assertSame('test', $qs['scope']);
 
         $url = $provider->getAuthorizationUrl(['scope' => ['foo', 'bar']]);
 
-        parse_str(parse_url($url, PHP_URL_QUERY), $qs);
+        parse_str((string) parse_url($url, PHP_URL_QUERY), $qs);
 
         $this->assertArrayHasKey('scope', $qs);
         $this->assertSame('foo,bar', $qs['scope']);
@@ -374,8 +379,8 @@ public function testAuthorizationStateIsRandom(): void
             // Repeat the test multiple times to verify state changes
             $url = $provider->getAuthorizationUrl();
 
-            parse_str(parse_url($url, PHP_URL_QUERY), $qs);
-
+            parse_str((string) parse_url($url, PHP_URL_QUERY), $qs);
+            $this->assertIsString($qs['state'] ?? null);
             $this->assertTrue(preg_match('/^[a-zA-Z0-9\/+]{32}$/', $qs['state']) === 1);
             $this->assertNotSame($qs['state'], $last);
 
@@ -402,7 +407,7 @@ public function testPkceMethod(string $pkceMethod, string $pkceCode, string $exp
         $url = $provider->getAuthorizationUrl();
         $this->assertSame($pkceCode, $provider->getPkceCode());
 
-        parse_str(parse_url($url, PHP_URL_QUERY), $qs);
+        parse_str((string) parse_url($url, PHP_URL_QUERY), $qs);
         $this->assertArrayHasKey('code_challenge', $qs);
         $this->assertArrayHasKey('code_challenge_method', $qs);
         $this->assertSame($pkceMethod, $qs['code_challenge_method']);
@@ -442,7 +447,7 @@ public function testPkceMethod(string $pkceMethod, string $pkceCode, string $exp
         $client
             ->shouldHaveReceived('sendRequest')
             ->once()
-            ->withArgs(function ($request) use ($pkceCode) {
+            ->withArgs(function (RequestInterface $request) use ($pkceCode) {
                 parse_str((string) $request->getBody(), $body);
 
                 return $body['code_verifier'] === $pkceCode;
@@ -487,7 +492,8 @@ public function testPkceCodeIsRandom(): void
             // Repeat the test multiple times to verify code_challenge changes
             $url = $provider->getAuthorizationUrl();
 
-            parse_str(parse_url($url, PHP_URL_QUERY), $qs);
+            parse_str((string) parse_url($url, PHP_URL_QUERY), $qs);
+            $this->assertIsString($qs['code_challenge'] ?? null);
             $this->assertTrue(preg_match('/^[a-zA-Z0-9-_]{43}$/', $qs['code_challenge']) === 1);
             $this->assertNotSame($qs['code_challenge'], $last);
             $last = $qs['code_challenge'];
@@ -497,6 +503,8 @@ public function testPkceCodeIsRandom(): void
     public function testPkceMethodIsDisabledByDefault(): void
     {
         $provider = $this->getAbstractProviderMock();
+        $provider->shouldAllowMockingProtectedMethods();
+        /** @phpstan-ignore method.protected */
         $pkceMethod = $provider->getPkceMethod();
         $this->assertNull($pkceMethod);
     }
@@ -561,7 +569,7 @@ public function testErrorResponsesCanBeCustomizedAtTheProvider(): void
         $client
             ->shouldHaveReceived('sendRequest')
             ->once()
-            ->withArgs(fn ($request) => $request->getMethod() === $method
+            ->withArgs(fn (RequestInterface $request) => $request->getMethod() === $method
                     && (string) $request->getUri() === $url);
     }
 
@@ -728,7 +736,7 @@ public function testGetAccessToken(string $method): void
         $provider->setHttpClient($client);
         $token = $provider->getAccessToken($grant, ['code' => 'mock_authorization_code']);
 
-        $this->assertInstanceOf(AccessTokenInterface::class, $token);
+        $this->assertInstanceOf(ResourceOwnerAccessTokenInterface::class, $token);
 
         $this->assertSame($rawResponse['resource_owner_id'], $token->getResourceOwnerId());
         $this->assertSame($rawResponse['access_token'], $token->getToken());
@@ -737,7 +745,7 @@ public function testGetAccessToken(string $method): void
         $client
             ->shouldHaveReceived('sendRequest')
             ->once()
-            ->withArgs(fn ($request) => $request->getMethod() === $provider->getAccessTokenMethod()
+            ->withArgs(fn (RequestInterface $request) => $request->getMethod() === $provider->getAccessTokenMethod()
                     && (string) $request->getUri() === $provider->getBaseAccessTokenUrl([]));
     }
 
@@ -868,7 +876,9 @@ protected function getAbstractProviderMock(): AbstractProvider & MockInterface
     public function testDefaultAccessTokenMethod(): void
     {
         $provider = $this->getAbstractProviderMock();
+        $provider->shouldAllowMockingProtectedMethods();
 
+        /** @phpstan-ignore method.protected */
         $method = $provider->getAccessTokenMethod();
 
         $expectedMethod = 'POST';
@@ -878,8 +888,11 @@ public function testDefaultAccessTokenMethod(): void
     public function testDefaultPrepareAccessTokenResponse(): void
     {
         $provider = Mockery::mock(Fake\ProviderWithAccessTokenResourceOwnerId::class)->makePartial();
+        $provider->shouldAllowMockingProtectedMethods();
 
         $result = ['user_id' => uniqid()];
+
+        /** @phpstan-ignore method.protected */
         $newResult = $provider->prepareAccessTokenResponse($result);
 
         $this->assertArrayHasKey('resource_owner_id', $newResult);
@@ -922,6 +935,8 @@ public function testPrepareAccessTokenResponseWithDotNotation(): void
             ->andReturn('user.id');
 
         $result = ['user' => ['id' => uniqid()]];
+
+        /** @phpstan-ignore method.protected */
         $newResult = $provider->prepareAccessTokenResponse($result);
 
         $this->assertArrayHasKey('resource_owner_id', $newResult);
@@ -937,6 +952,8 @@ public function testPrepareAccessTokenResponseWithInvalidKeyType(): void
             ->andReturn(new stdClass());
 
         $result = ['user_id' => uniqid()];
+
+        /** @phpstan-ignore method.protected */
         $newResult = $provider->prepareAccessTokenResponse($result);
 
         $this->assertFalse(isset($newResult['resource_owner_id']));
@@ -951,6 +968,8 @@ public function testPrepareAccessTokenResponseWithInvalidKeyPath(): void
             ->andReturn('user.name');
 
         $result = ['user' => ['id' => uniqid()]];
+
+        /** @phpstan-ignore method.protected */
         $newResult = $provider->prepareAccessTokenResponse($result);
 
         $this->assertFalse(isset($newResult['resource_owner_id']));
@@ -959,7 +978,9 @@ public function testPrepareAccessTokenResponseWithInvalidKeyPath(): void
     public function testDefaultAuthorizationHeaders(): void
     {
         $provider = $this->getAbstractProviderMock();
+        $provider->shouldAllowMockingProtectedMethods();
 
+        /** @phpstan-ignore method.protected */
         $headers = $provider->getAuthorizationHeaders();
 
         $this->assertEquals([], $headers);
diff --git a/test/src/Provider/Exception/IdentityProviderExceptionTest.php b/test/src/Provider/Exception/IdentityProviderExceptionTest.php
index 900b3aa6..53308118 100644
--- a/test/src/Provider/Exception/IdentityProviderExceptionTest.php
+++ b/test/src/Provider/Exception/IdentityProviderExceptionTest.php
@@ -9,7 +9,7 @@
 
 class IdentityProviderExceptionTest extends TestCase
 {
-    public function testIdentityProviderException()
+    public function testIdentityProviderException(): void
     {
         $result = [
             'error' => 'message',
diff --git a/test/src/Provider/Fake.php b/test/src/Provider/Fake.php
index 6c0ffde2..75c9f54a 100644
--- a/test/src/Provider/Fake.php
+++ b/test/src/Provider/Fake.php
@@ -10,6 +10,10 @@
 use League\OAuth2\Client\Tool\BearerAuthorizationTrait;
 use Psr\Http\Message\ResponseInterface;
 
+use function assert;
+use function is_int;
+use function is_string;
+
 class Fake extends AbstractProvider
 {
     use BearerAuthorizationTrait;
@@ -105,6 +109,8 @@ protected function getRandomPkceCode($length = 64)
     }
 
     /**
+     * @param array{id?: mixed, email?: string, name?: string} $response
+     *
      * @inheritDoc
      */
     protected function createResourceOwner(array $response, AccessToken $token)
@@ -118,6 +124,9 @@ protected function createResourceOwner(array $response, AccessToken $token)
     protected function checkResponse(ResponseInterface $response, $data)
     {
         if (isset($data['error'])) {
+            assert(is_string($data['error']));
+            assert(is_int($data['code']));
+
             throw new IdentityProviderException($data['error'], $data['code'], $data);
         }
     }
diff --git a/test/src/Provider/Fake/ProviderWithAccessTokenHints.php b/test/src/Provider/Fake/ProviderWithAccessTokenHints.php
index a826d039..297981a1 100644
--- a/test/src/Provider/Fake/ProviderWithAccessTokenHints.php
+++ b/test/src/Provider/Fake/ProviderWithAccessTokenHints.php
@@ -7,6 +7,7 @@
 use League\OAuth2\Client\Provider\GenericProvider;
 use League\OAuth2\Client\Provider\GenericResourceOwner;
 use League\OAuth2\Client\Token\AccessToken;
+use League\OAuth2\Client\Token\AccessTokenInterface;
 use League\OAuth2\Client\Tool\MacAuthorizationTrait;
 
 class ProviderWithAccessTokenHints extends GenericProvider
@@ -26,7 +27,7 @@ public function getResourceOwnerDetailsUrl(AccessToken $token)
      */
     protected function createResourceOwner(array $response, AccessToken $token)
     {
-        return new GenericResourceOwner($response, $token->getResourceOwnerId());
+        return new GenericResourceOwner($response, (string) $token->getResourceOwnerId());
     }
 
     /**
@@ -45,18 +46,12 @@ protected function fetchResourceOwnerDetails(AccessToken $token)
         return [];
     }
 
-    /**
-     * @inheritDoc
-     */
-    protected function getTokenId(AccessToken $token)
+    protected function getTokenId(AccessTokenInterface | string | null $token): string
     {
         return 'fake_token_id';
     }
 
-    /**
-     * @inheritDoc
-     */
-    protected function getMacSignature($id, $ts, $nonce)
+    protected function getMacSignature(string $id, int $ts, string $nonce): string
     {
         return 'fake_mac_signature';
     }
diff --git a/test/src/Provider/Fake/User.php b/test/src/Provider/Fake/User.php
index 23060961..c86dcf59 100644
--- a/test/src/Provider/Fake/User.php
+++ b/test/src/Provider/Fake/User.php
@@ -9,12 +9,12 @@
 class User implements ResourceOwnerInterface
 {
     /**
-     * @var array<array-key, mixed>
+     * @var array{id?: mixed, email?: string, name?: string}
      */
     protected array $response;
 
     /**
-     * @param array<array-key, mixed> $response
+     * @param array{id?: mixed, email?: string, name?: string} $response
      */
     public function __construct(array $response)
     {
@@ -26,23 +26,23 @@ public function __construct(array $response)
      */
     public function getId()
     {
-        return $this->response['id'];
+        return $this->response['id'] ?? null;
     }
 
     public function getUserEmail(): ?string
     {
-        return $this->response['email'];
+        return $this->response['email'] ?? null;
     }
 
     public function getUserScreenName(): ?string
     {
-        return $this->response['name'];
+        return $this->response['name'] ?? null;
     }
 
     /**
      * @inheritDoc
      */
-    public function toArray()
+    public function toArray(): array
     {
         return $this->response;
     }
diff --git a/test/src/Provider/Generic.php b/test/src/Provider/Generic.php
index 378a364d..2bd6f0f3 100644
--- a/test/src/Provider/Generic.php
+++ b/test/src/Provider/Generic.php
@@ -4,14 +4,25 @@
 
 namespace League\OAuth2\Client\Test\Provider;
 
+use League\OAuth2\Client\Grant\GrantFactory;
+use League\OAuth2\Client\OptionProvider\OptionProviderInterface;
 use League\OAuth2\Client\Provider\GenericProvider;
 use League\OAuth2\Client\Token\AccessToken;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestFactoryInterface;
+use Psr\Http\Message\StreamFactoryInterface;
 
 class Generic extends GenericProvider
 {
     /**
      * @param array<string, mixed> $options
-     * @param array<string, mixed> $collaborators
+     * @param array{
+     *     grantFactory?: GrantFactory,
+     *     requestFactory?: RequestFactoryInterface,
+     *     streamFactory?: StreamFactoryInterface,
+     *     httpClient?: ClientInterface,
+     *     optionProvider?: OptionProviderInterface,
+     * } $collaborators
      */
     public function __construct(array $options = [], array $collaborators = [])
     {
diff --git a/test/src/Provider/GenericProviderTest.php b/test/src/Provider/GenericProviderTest.php
index 99fc5d84..658813a0 100644
--- a/test/src/Provider/GenericProviderTest.php
+++ b/test/src/Provider/GenericProviderTest.php
@@ -163,7 +163,7 @@ public function testCheckResponse(): void
      * @param array<string, mixed> $extraOptions Any extra options to configure the generic provider with.
      */
     #[DataProvider('checkResponseThrowsExceptionProvider')]
-    public function testCheckResponseThrowsException(array $error, array $extraOptions = [])
+    public function testCheckResponseThrowsException(array $error, array $extraOptions = []): void
     {
         $response = Mockery::mock(ResponseInterface::class);
 
diff --git a/test/src/Token/AccessTokenTest.php b/test/src/Token/AccessTokenTest.php
index aa5ced5a..1126db80 100644
--- a/test/src/Token/AccessTokenTest.php
+++ b/test/src/Token/AccessTokenTest.php
@@ -271,7 +271,7 @@ public function testJsonSerializable(): void
         $token = $this->getAccessToken($options);
         $jsonToken = json_encode($token);
 
-        $this->assertEquals($options, json_decode($jsonToken, true));
+        $this->assertEquals($options, json_decode((string) $jsonToken, true));
 
         self::tearDownForBackwardsCompatibility();
     }
diff --git a/test/src/Tool/ProviderRedirectTraitTest.php b/test/src/Tool/ProviderRedirectTraitTest.php
index c35e6302..227627a2 100644
--- a/test/src/Tool/ProviderRedirectTraitTest.php
+++ b/test/src/Tool/ProviderRedirectTraitTest.php
@@ -89,7 +89,7 @@ public function testClientLimitsRedirectResponse(): void
 
         $client = Mockery::mock(ClientInterface::class);
         $client
-            ->shouldReceive('send')
+            ->shouldReceive('sendRequest')
             ->times($redirectLimit)
             ->andReturn($response);
 
@@ -119,7 +119,7 @@ public function testClientLimitsRedirectLoopWhenRedirectNotDetected(): void
 
         $client = Mockery::mock(ClientInterface::class);
         $client
-            ->shouldReceive('send')
+            ->shouldReceive('sendRequest')
             ->once()
             ->andReturn($response);
 
@@ -146,7 +146,7 @@ public function testClientErrorReturnsResponse(): void
 
         $client = Mockery::mock(ClientInterface::class);
         $client
-            ->shouldReceive('send')
+            ->shouldReceive('sendRequest')
             ->andThrow($exception);
 
         $this->setHttpClient($client);
diff --git a/test/src/Tool/QueryBuilderTraitTest.php b/test/src/Tool/QueryBuilderTraitTest.php
index d7e0394c..e30f3d7b 100644
--- a/test/src/Tool/QueryBuilderTraitTest.php
+++ b/test/src/Tool/QueryBuilderTraitTest.php
@@ -13,7 +13,7 @@ class QueryBuilderTraitTest extends TestCase
 {
     use QueryBuilderTrait;
 
-    public function testBuildQueryString()
+    public function testBuildQueryString(): void
     {
         ini_set('arg_separator.output', '&amp;');