diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..792fbb4
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,267 @@
+"""Pytest configuration and fixtures for OpenAPI Mock Generator tests."""
+
+import pytest
+import tempfile
+import json
+from pathlib import Path
+
+
+@pytest.fixture
+def temp_dir():
+    """Create a temporary directory for tests."""
+    with tempfile.TemporaryDirectory() as tmpdir:
+        yield Path(tmpdir)
+
+
+@pytest.fixture
+def sample_openapi_yaml():
+    """Sample OpenAPI specification in YAML format."""
+    return """
+openapi: \"3.0.0\"
+info:
+  title: Sample API
+  version: \"1.0.0\"
+paths:
+  /users:
+    get:
+      summary: Get all users
+      parameters:
+        - name: page
+          in: query
+          schema:
+            type: integer
+        - name: limit
+          in: query
+          schema:
+            type: integer
+      responses:
+        '200':
+          description: Successful response
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  type: object
+                  properties:
+                    id:
+                      type: integer
+                    name:
+                      type: string
+                    email:
+                      type: string
+                      format: email
+                    createdAt:
+                      type: string
+                      format: date-time
+  /users/{userId}:
+    get:
+      summary: Get user by ID
+      parameters:
+        - name: userId
+          in: path
+          required: true
+          schema:
+            type: integer
+      responses:
+        '200':
+          description: Successful response
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  id:
+                    type: integer
+                  name:
+                    type: string
+                  email:
+                    type: string
+                    format: email
+        '404':
+          description: User not found
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  error:
+                    type: string
+                  message:
+                    type: string
+    put:
+      summary: Update user
+      parameters:
+        - name: userId
+          in: path
+          required: true
+          schema:
+            type: integer
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              type: object
+              properties:
+                name:
+                  type: string
+                email:
+                  type: string
+                  format: email
+              required:
+                - name
+      responses:
+        '200':
+          description: User updated
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  id:
+                    type: integer
+                  name:
+                    type: string
+  /posts:
+    post:
+      summary: Create a post
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              type: object
+              properties:
+                title:
+                  type: string
+                content:
+                  type: string
+                authorId:
+                  type: integer
+      responses:
+        '201':
+          description: Post created
+          content:
+            application/json:
+              schema:
+                type: object
+                properties:
+                  id:
+                    type: integer
+                  title:
+                    type: string
+                  content:
+                    type: string
+                  authorId:
+                    type: integer
+                  publishedAt:
+                    type: string
+                    format: date-time
+components:
+  schemas:
+    User:
+      type: object
+      properties:
+        id:
+          type: integer
+        name:
+          type: string
+        email:
+          type: string
+          format: email
+        createdAt:
+          type: string
+          format: date-time
+    Post:
+      type: object
+      properties:
+        id:
+          type: integer
+        title:
+          type: string
+        content:
+          type: string
+        authorId:
+          type: integer
+        publishedAt:
+          type: string
+          format: date-time
+    Error:
+      type: object
+      properties:
+        error:
+          type: string
+        message:
+          type: string
+"""
+
+
+@pytest.fixture
+def sample_openapi_json():
+    """Sample OpenAPI specification in JSON format."""
+    return json.dumps({
+        "openapi": "3.0.0",
+        "info": {
+            "title": "Sample API",
+            "version": "1.0.0"
+        },
+        "paths": {
+            "/users": {
+                "get": {
+                    "summary": "Get all users",
+                    "responses": {
+                        "200": {
+                            "description": "Success",
+                            "content": {
+                                "application/json": {
+                                    "schema": {
+                                        "type": "array",
+                                        "items": {
+                                            "type": "object",
+                                            "properties": {
+                                                "id": {"type": "integer"},
+                                                "name": {"type": "string"}
+                                            }
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }, indent=2)
+
+
+@pytest.fixture
+def invalid_openapi_yaml():
+    """Invalid OpenAPI specification (missing openapi version)."""
+    return """
+info:
+  title: Invalid API
+  version: \"1.0.0\"
+paths:
+  /users:
+    get:
+      responses:
+        '200':
+          description: Success
+"""
+
+
+@pytest.fixture
+def temp_spec_file(sample_openapi_yaml, tmp_path):
+    """Create a temporary OpenAPI spec file."""
+    spec_file = tmp_path / "openapi.yaml"
+    spec_file.write_text(sample_openapi_yaml)
+    return str(spec_file)
+
+
+@pytest.fixture
+def temp_json_spec_file(sample_openapi_json, tmp_path):
+    """Create a temporary OpenAPI spec file in JSON format."""
+    spec_file = tmp_path / "openapi.json"
+    spec_file.write_text(sample_openapi_json)
+    return str(spec_file)