diff --git a/testing.rst b/testing.rst
index e8830bf..70ba36d 100644
--- a/testing.rst
+++ b/testing.rst
@@ -1,11 +1,34 @@
 Testing Guide
 =============
 
+Test Infrastructure Overview
+----------------------------
+
+We implemented multiple types of tests in SD-Fabric.
+
+- **Unit Test**
+
+  - Verify codes at the level of methods or classes, and therefore covers a lot of details in a small scope.
+  - Run before merge as part of the CI/CD process of each component.
+
+- **Component Test**
+
+  - Verify a component with its dependencies as a whole.
+  - Run as sanity checks before merge as part of the CI/CD process of each component.
+
+- **System Integration Test**
+
+  - Verify the entire SD-Fabric solution,
+    involving multiple components and including various failure scenarios.
+  - Run nightly
+
+.. image:: images/test-overview.png
+  :width: 800px
 
 .. toctree::
    :maxdepth: 2
    :glob:
 
-   testing/system
    testing/component
    testing/pipeline
+   testing/system