Add Add test::stream::lowest_layer:

This allows the stream to be used as the next layer type in
a stack of network stream layers.

Signed-off-by: Damian Jarek <damian.jarek93@gmail.com>

CHANGELOG.md

@@ -3,6 +3,7 @@ Version 110:
 * Refactor stream open state variable
 * Refactor websocket stream members
 * Refactor websocket stream: fixes and tests
+* Add test::stream::lowest_layer
 
 --------------------------------------------------------------------------------
 

test/extras/include/boost/beast/test/stream.hpp

@@ -113,6 +113,9 @@ class stream
 public:
     using buffer_type = flat_buffer;
 
+    /// The type of the lowest layer.
+    using lowest_layer_type = stream;
+
     /// Destructor
     ~stream()
     {
@@ -209,6 +212,34 @@ public:
         return in_->ios;
     }
 
+    /** Get a reference to the lowest layer
+
+        This function returns a reference to the lowest layer
+        in a stack of stream layers.
+
+        @return A reference to the lowest layer in the stack of
+        stream layers.
+    */
+    lowest_layer_type&
+    lowest_layer()
+    {
+        return *this;
+    }
+
+    /** Get a reference to the lowest layer
+
+        This function returns a reference to the lowest layer
+        in a stack of stream layers.
+
+        @return A reference to the lowest layer in the stack of
+        stream layers. Ownership is not transferred to the caller.
+    */
+    lowest_layer_type const&
+    lowest_layer() const
+    {
+        return *this;
+    }
+
     /// Set the maximum number of bytes returned by read_some
     void
     read_size(std::size_t n)