diff --git a/src/Contracts/Resources/GenerativeModelContract.php b/src/Contracts/Resources/GenerativeModelContract.php
index 191a8de..dd97e5d 100644
--- a/src/Contracts/Resources/GenerativeModelContract.php
+++ b/src/Contracts/Resources/GenerativeModelContract.php
@@ -6,6 +6,8 @@
 
 use Gemini\Data\Blob;
 use Gemini\Data\Content;
+use Gemini\Data\GenerationConfig;
+use Gemini\Data\SafetySetting;
 use Gemini\Resources\ChatSession;
 use Gemini\Responses\GenerativeModel\CountTokensResponse;
 use Gemini\Responses\GenerativeModel\GenerateContentResponse;
@@ -33,4 +35,8 @@ public function streamGenerateContent(string|Blob|array|Content ...$parts): Stre
      * @param  array<Content>  $history
      */
     public function startChat(array $history = []): ChatSession;
+
+    public function withSafetySetting(SafetySetting $safetySetting): self;
+
+    public function withGenerationConfig(GenerationConfig $generationConfig): self;
 }
diff --git a/src/Testing/ClientFake.php b/src/Testing/ClientFake.php
index c491906..a4b914f 100644
--- a/src/Testing/ClientFake.php
+++ b/src/Testing/ClientFake.php
@@ -8,6 +8,7 @@
 use Gemini\Contracts\ResponseContract;
 use Gemini\Enums\ModelType;
 use Gemini\Responses\StreamResponse;
+use Gemini\Testing\FunctionCalls\TestFunctionCall;
 use Gemini\Testing\Requests\TestRequest;
 use Gemini\Testing\Resources\ChatSessionTestResource;
 use Gemini\Testing\Resources\EmbeddingModelTestResource;
@@ -23,6 +24,11 @@ class ClientFake implements ClientContract
      */
     private array $requests = [];
 
+    /**
+     * @var array<array-key, TestFunctionCall>
+     */
+    private array $functionCalls = [];
+
     /**
      * @param  array<array-key, ResponseContract>  $responses
      */
@@ -125,6 +131,80 @@ public function record(TestRequest $request): ResponseContract|StreamResponse
         return $response;
     }
 
+    public function assertFunctionCalled(string $resource, ModelType|string|null $model = null, callable|int|null $callback = null): void
+    {
+        if (is_int($callback)) {
+            $this->assertFunctionCalledTimes(resource: $resource, model: $model, times: $callback);
+
+            return;
+        }
+
+        PHPUnit::assertTrue(
+            $this->functionCalled(resource: $resource, model: $model, callback: $callback) !== [],
+            "The expected [{$resource}] function was not called."
+        );
+    }
+
+    private function assertFunctionCalledTimes(string $resource, ModelType|string|null $model = null, int $times = 1): void
+    {
+        $count = count($this->functionCalled(resource: $resource, model: $model));
+
+        PHPUnit::assertSame(
+            $times, $count,
+            "The expected [{$resource}] resource was called {$count} times instead of {$times} times."
+        );
+    }
+
+    /**
+     * @return mixed[]
+     */
+    private function functionCalled(string $resource, ModelType|string|null $model = null, ?callable $callback = null): array
+    {
+        if (! $this->hasFunctionCalled(resource: $resource, model: $model)) {
+            return [];
+        }
+
+        $callback = $callback ?: fn (): bool => true;
+
+        return array_filter($this->resourcesOfFunctionCalls(type: $resource), fn (TestFunctionCall $functionCall) => $callback($functionCall->method(), $functionCall->args()));
+    }
+
+    private function hasFunctionCalled(string $resource, ModelType|string|null $model = null): bool
+    {
+        return $this->resourcesOfFunctionCalls(type: $resource, model: $model) !== [];
+    }
+
+    public function assertFunctionNotCalled(string $resource, ModelType|string|null $model = null, ?callable $callback = null): void
+    {
+        PHPUnit::assertCount(
+            0, $this->functionCalled(resource: $resource, model: $model, callback: $callback),
+            "The unexpected [{$resource}] function was called."
+        );
+    }
+
+    public function assertNoFunctionsCalled(): void
+    {
+        $resourceNames = implode(
+            separator: ', ',
+            array: array_map(fn (TestFunctionCall $functionCall): string => $functionCall->resource(), $this->functionCalls)
+        );
+
+        PHPUnit::assertEmpty($this->functionCalls, 'The following functions were called unexpectedly: '.$resourceNames);
+    }
+
+    /**
+     * @return array<array-key, TestFunctionCall>
+     */
+    private function resourcesOfFunctionCalls(string $type, ModelType|string|null $model = null): array
+    {
+        return array_filter($this->functionCalls, fn (TestFunctionCall $functionCall): bool => $functionCall->resource() === $type && ($model === null || $functionCall->model() === $model));
+    }
+
+    public function recordFunctionCall(TestFunctionCall $call): void
+    {
+        $this->functionCalls[] = $call;
+    }
+
     public function models(): ModelTestResource
     {
         return new ModelTestResource(fake: $this);
diff --git a/src/Testing/FunctionCalls/TestFunctionCall.php b/src/Testing/FunctionCalls/TestFunctionCall.php
new file mode 100644
index 0000000..44ef1c4
--- /dev/null
+++ b/src/Testing/FunctionCalls/TestFunctionCall.php
@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Gemini\Testing\FunctionCalls;
+
+use Gemini\Enums\ModelType;
+
+final class TestFunctionCall
+{
+    /**
+     * @param  array<string, mixed>  $args
+     */
+    public function __construct(protected string $resource, protected string $method, protected array $args, protected ModelType|string|null $model = null) {}
+
+    public function resource(): string
+    {
+        return $this->resource;
+    }
+
+    public function method(): string
+    {
+        return $this->method;
+    }
+
+    /**
+     * @return array<string, mixed>
+     */
+    public function args(): array
+    {
+        return $this->args;
+    }
+
+    public function model(): ModelType|string|null
+    {
+        return $this->model;
+    }
+}
diff --git a/src/Testing/Resources/Concerns/Testable.php b/src/Testing/Resources/Concerns/Testable.php
index 89e9701..b6912c2 100644
--- a/src/Testing/Resources/Concerns/Testable.php
+++ b/src/Testing/Resources/Concerns/Testable.php
@@ -8,6 +8,7 @@
 use Gemini\Enums\ModelType;
 use Gemini\Responses\StreamResponse;
 use Gemini\Testing\ClientFake;
+use Gemini\Testing\FunctionCalls\TestFunctionCall;
 use Gemini\Testing\Requests\TestRequest;
 
 trait Testable
@@ -30,4 +31,19 @@ public function assertNotSent(callable|int|null $callback = null): void
     {
         $this->fake->assertNotSent(resource: $this->resource(), model: $this->model, callback: $callback);
     }
+
+    public function recordFunctionCall(string $method, array $args = [], ModelType|string|null $model = null): void
+    {
+        $this->fake->recordFunctionCall(new TestFunctionCall(resource: $this->resource(), method: $method, args: $args, model: $model));
+    }
+
+    public function assertFunctionCalled(callable|int|null $callback = null): void
+    {
+        $this->fake->assertFunctionCalled(resource: $this->resource(), model: $this->model, callback: $callback);
+    }
+
+    public function assertFunctionNotCalled(callable|int|null $callback = null): void
+    {
+        $this->fake->assertFunctionNotCalled(resource: $this->resource(), model: $this->model, callback: $callback);
+    }
 }
diff --git a/src/Testing/Resources/GenerativeModelTestResource.php b/src/Testing/Resources/GenerativeModelTestResource.php
index cc00a34..7f92723 100644
--- a/src/Testing/Resources/GenerativeModelTestResource.php
+++ b/src/Testing/Resources/GenerativeModelTestResource.php
@@ -7,6 +7,8 @@
 use Gemini\Contracts\Resources\GenerativeModelContract;
 use Gemini\Data\Blob;
 use Gemini\Data\Content;
+use Gemini\Data\GenerationConfig;
+use Gemini\Data\SafetySetting;
 use Gemini\Resources\ChatSession;
 use Gemini\Resources\GenerativeModel;
 use Gemini\Responses\GenerativeModel\CountTokensResponse;
@@ -42,4 +44,18 @@ public function startChat(array $history = []): ChatSession
     {
         return $this->record(method: __FUNCTION__, args: func_get_args(), model: $this->model);
     }
+
+    public function withSafetySetting(SafetySetting $safetySetting): self
+    {
+        $this->recordFunctionCall(method: __FUNCTION__, args: func_get_args(), model: $this->model);
+
+        return $this;
+    }
+
+    public function withGenerationConfig(GenerationConfig $generationConfig): self
+    {
+        $this->recordFunctionCall(method: __FUNCTION__, args: func_get_args(), model: $this->model);
+
+        return $this;
+    }
 }
diff --git a/tests/Testing/Resources/GenerativeModelTestResource.php b/tests/Testing/Resources/GenerativeModelTestResource.php
index d84dfc6..a50383b 100644
--- a/tests/Testing/Resources/GenerativeModelTestResource.php
+++ b/tests/Testing/Resources/GenerativeModelTestResource.php
@@ -2,6 +2,10 @@
 
 declare(strict_types=1);
 
+use Gemini\Data\GenerationConfig;
+use Gemini\Data\SafetySetting;
+use Gemini\Enums\HarmBlockThreshold;
+use Gemini\Enums\HarmCategory;
 use Gemini\Responses\GenerativeModel\CountTokensResponse;
 use Gemini\Responses\GenerativeModel\GenerateContentResponse;
 use Gemini\Testing\ClientFake;
@@ -44,3 +48,48 @@
             $parameters[0] === 'Hello';
     });
 });
+
+it('records a "withSafetySetting" function call', function () {
+    $fake = new ClientFake;
+
+    $safetySetting = new SafetySetting(HarmCategory::HARM_CATEGORY_DANGEROUS, HarmBlockThreshold::BLOCK_ONLY_HIGH);
+
+    $fake->geminiPro()->withSafetySetting($safetySetting);
+
+    $fake->geminiPro()->assertFunctionCalled(function (string $method, array $parameters) use ($safetySetting) {
+        return $method === 'withSafetySetting' &&
+            $parameters[0] === $safetySetting;
+    });
+});
+
+it('records a "withGenerationConfig" function call', function () {
+    $fake = new ClientFake;
+
+    $generationConfig = new GenerationConfig;
+
+    $fake->geminiPro()->withGenerationConfig($generationConfig);
+
+    $fake->geminiPro()->assertFunctionCalled(function (string $method, array $parameters) use ($generationConfig) {
+        return $method === 'withGenerationConfig' &&
+            $parameters[0] === $generationConfig;
+    });
+});
+
+it('records both content request and function call', function () {
+    $fake = new ClientFake([
+        GenerateContentResponse::fake(),
+    ]);
+
+    $generationConfig = new GenerationConfig;
+
+    $fake->geminiPro()->withGenerationConfig($generationConfig)->generateContent('Hello');
+
+    $fake->geminiPro()->assertSent(function (string $method, array $parameters) {
+        return $method === 'generateContent' &&
+            $parameters[0] === 'Hello';
+    });
+    $fake->geminiPro()->assertFunctionCalled(function (string $method, array $parameters) use ($generationConfig) {
+        return $method === 'withGenerationConfig' &&
+            $parameters[0] === $generationConfig;
+    });
+});