1 files changed, 129 insertions, 0 deletions
diff --git a/docs/pages/14-testing.md b/docs/pages/14-testing.md
new file mode 100644
index 0000000..789da96
--- /dev/null
+++ b/docs/pages/14-testing.md
@@ -0,0 +1,129 @@
+<h1 align="center">Testing Your Program</h1>
+<p align="center">
+    Writing unit tests for Chain and Renderer
+</p>
+
+A built-in benefit of the pipeline model is **testability**.
+
+A Chain is just a function that takes input and returns output; a Renderer is just a function that takes input and writes content — no global state magic, testing is straightforward.
+
+## Testing Renderer
+
+Renderer is the easiest to test — call the function, assert the result:
+
+```rust
+@@@pack!(ResultName = String);
+// Returns String instead of ()
+#[renderer]
+fn render_name(name: ResultName) -> String {
+    r_println!("Hello, {}!", *name);
+}
+ 
+#[test]
+fn test_render_name() {
+    let result = render_name(ResultName::new("Alice".to_string()));
+    assert_eq!(result, "Hello, Alice!\n");
+}
+```
+ 
+Note the Renderer's return type changed to `-> String` — `#[renderer]` auto-converts `RenderResult` to whatever return type you specify (default is `()`). By returning `String`, you can directly assert on the output content.
+
+## Testing Chain
+
+Testing a Chain is slightly more complex because its return value is `Next` (actually `impl Into<ChainProcess<ThisProgram>>`). You'll need the assertion macros provided by the framework:
+
+```rust
+@@@use mingling::{assert_member_id, assert_render_result, unpack_chain_process};
+@@@dispatcher!("hello", CMDHello => EntryHello);
+@@@pack!(ResultName = String);
+@@@pack!(ErrorNoName = ());
+@@@#[chain]
+@@@fn handle_hello(args: EntryHello) -> Next {
+@@@    let name = args.inner.first().cloned().unwrap_or_default();
+@@@    if name.is_empty() {
+@@@        ErrorNoName::default().to_render()
+@@@    } else {
+@@@        ResultName::new(name).to_render()
+@@@    }
+@@@}
+#[test]
+fn test_handle_hello_with_name() {
+    let chain_process = handle_hello(EntryGreet::new(vec!["Alice".to_string()])).into();
+    // Asserts this is a render result (not continuing the chain)
+    assert_render_result!(chain_process);
+    // Asserts member_id is ResultName
+    assert_member_id!(chain_process, ResultName);
+    // Unpacks the inner value
+    let result_name = unpack_chain_process!(chain_process, ResultName);
+    assert_eq!(result_name.inner, "Alice");
+}
+```
+ 
+What the three test macros do:
+
+| Macro                   | Function                                                          |
+| ----------------------- | ----------------------------------------------------------------- |
+| `assert_render_result!` | Asserts Chain returned the render path (not continuing the chain) |
+| `assert_member_id!`     | Asserts the return value's member ID is a certain type            |
+| `unpack_chain_process!` | Unpacks the original type from ChainProcess                       |
+
+## Constructing Data with the entry! Macro
+
+If `extra_macros` is enabled, you can use `entry!` to quickly construct an Entry:
+
+```rust
+// Features: ["extra_macros"]
+ 
+@@@use mingling::{assert_member_id, unpack_chain_process};
+@@@use mingling::macros::entry;
+@@@dispatcher!("hello", CMDHello => EntryHello);
+@@@pack!(ResultName = String);
+@@@#[chain]
+@@@fn handle_hello(args: EntryHello) -> Next {
+@@@    let name = args.inner.first().cloned().unwrap_or_default();
+@@@    ResultName::new(name).to_render()
+@@@}
+#[test]
+fn test_with_entry_macro() {
+    // entry! constructs an Entry from string literals
+    let entry = entry!("--name", "Alice");
+    let chain_process = handle_hello(entry).into();
+    let result_name = unpack_chain_process!(chain_process, ResultName);
+    assert_eq!(result_name.inner, "Alice");
+}
+```
+ 
+## Testing Resource Injection
+
+If a Chain uses resources, you need to provide resource instances in the test:
+
+```rust
+@@@use mingling::{assert_render_result, unpack_chain_process};
+@@@#[derive(Default, Clone)]
+@@@struct ResPrefix(String);
+@@@dispatcher!("hello", CMDHello => EntryHello);
+@@@pack!(ResultGreeting = String);
+@@@
+#[chain]
+fn handle_hello(args: EntryHello, prefix: &ResPrefix) -> Next {
+    let name = args.inner.first().cloned().unwrap_or_default();
+    ResultGreeting::new(format!("{}, {}", prefix.0, name)).to_render()
+}
+ 
+#[test]
+fn test_handle_with_resource() {
+    // Resources need to be passed manually in tests
+    let result = handle_hello(
+        EntryHello::new(vec!["World".to_string()]),
+        &ResPrefix("Hello".to_string()),
+    );
+    let greeting = unpack_chain_process!(result, ResultGreeting, ThisProgram);
+    assert_eq!(greeting.inner, "Hello, World");
+}
+```
+ 
+The pipeline model makes testing simple: each Chain and Renderer is a relatively independent function — construct input, assert output.
+
+<p align="center" style="font-size: 0.85em; color: clear;">
+    Written by @Weicao-CatilGrass
+</p>