adding common interfaces koan

about_common_interfaces.go

@@ -0,0 +1,32 @@
+package go_koans
+
+import "bytes"
+
+func aboutCommonInterfaces() {
+  {
+    in := new(bytes.Buffer)
+    in.WriteString("hello world")
+
+    out := new(bytes.Buffer)
+
+    /*
+       Your code goes here.
+       Hint, use these resources:
+
+       $ godoc -http=:8080
+       $ open http://localhost:8080/pkg/io/
+       $ open http://localhost:8080/pkg/bytes/
+    */
+
+    assert(out.String() == "hello world") // get data from the io.Reader to the io.Writer
+  }
+
+  {
+    in := new(bytes.Buffer)
+    in.WriteString("hello world")
+
+    out := new(bytes.Buffer)
+
+    assert(out.String() == "hello") // duplicate only a portion of the io.Reader
+  }
+}

setup_koans_test.go

@@ -32,6 +32,7 @@ func TestKoans(t *testing.T) {
   aboutVariadicFunctions()
   aboutFiles()
   aboutInterfaces()
+  aboutCommonInterfaces()
   aboutMaps()
   aboutPointers()
   aboutStructs()