Updated test case documentation

docs/test_cases/t20029.md

@@ -0,0 +1,102 @@
+# t20029 - Combined feature sequence diagram test case
+## Config
+```yaml
+compilation_database_dir: ..
+output_directory: puml
+diagrams:
+  t20029_sequence:
+    type: sequence
+    glob:
+      - ../../tests/t20029/t20029.cc
+    include:
+      namespaces:
+        - clanguml::t20029
+    exclude:
+      access:
+        - private
+    using_namespace:
+      - clanguml::t20029
+    start_from:
+      - function: "clanguml::t20029::tmain()"
+```
+## Source code
+File t20029.cc
+```cpp
+#include <atomic>
+#include <functional>
+#include <iostream>
+#include <memory>
+#include <string>
+
+namespace clanguml {
+namespace t20029 {
+using encoder_function_t = std::function<std::string(std::string &&)>;
+
+std::string encode_b64(std::string &&content) { return std::move(content); }
+
+template <typename T> class Encoder : public T {
+public:
+    bool send(std::string &&msg)
+    {
+        auto encoded = encode(std::move(msg));
+        return T::send(std::move(encoded));
+    }
+
+protected:
+    std::string encode(std::string &&msg) { return encode_b64(std::move(msg)); }
+
+private:
+    encoder_function_t f_;
+};
+
+template <typename T> class Retrier : public T {
+public:
+    bool send(std::string &&msg)
+    {
+        std::string buffer{std::move(msg)};
+
+        int retryCount = 5;
+
+        while (retryCount--) {
+            if (T::send(buffer))
+                return true;
+        }
+
+        return false;
+    }
+};
+
+class ConnectionPool {
+public:
+    void connect()
+    {
+        if (!is_connected_.load())
+            connect_impl();
+    }
+
+    bool send(const std::string &msg) { return true; }
+
+private:
+    void connect_impl() { is_connected_ = true; }
+
+    std::atomic<bool> is_connected_;
+};
+
+int tmain()
+{
+    auto pool = std::make_shared<Encoder<Retrier<ConnectionPool>>>();
+
+    pool->connect();
+
+    for (std::string line; std::getline(std::cin, line);) {
+        if (!pool->send(std::move(line)))
+            break;
+    }
+
+    return 0;
+}
+}
+}
+```
+## Generated UML diagrams
+![t20029_sequence](./t20029_sequence.svg "Combined feature sequence diagram test case")