Implement Cache as https://github.com/kataras/iris/issues/513

I love coding unique Iris staff!!!

cache_test.go

@@ -0,0 +1,92 @@
+package iris_test
+
+import (
+	"github.com/kataras/iris"
+	"github.com/kataras/iris/httptest"
+	"testing"
+	"time"
+)
+
+var testMarkdownContents = `## Hello Markdown from Iris
+
+This is an example of Markdown with Iris
+
+
+
+Features
+--------
+
+All features of Sundown are supported, including:
+
+*   **Compatibility**. The Markdown v1.0.3 test suite passes with
+    the --tidy option.  Without --tidy, the differences are
+    mostly in whitespace and entity escaping, where blackfriday is
+    more consistent and cleaner.
+
+*   **Common extensions**, including table support, fenced code
+    blocks, autolinks, strikethroughs, non-strict emphasis, etc.
+
+*   **Safety**. Blackfriday is paranoid when parsing, making it safe
+    to feed untrusted user input without fear of bad things
+    happening. The test suite stress tests this and there are no
+    known inputs that make it crash.  If you find one, please let me
+    know and send me the input that does it.
+
+    NOTE: "safety" in this context means *runtime safety only*. In order to
+    protect yourself against JavaScript injection in untrusted content, see
+    [this example](https://github.com/russross/blackfriday#sanitize-untrusted-content).
+
+*   **Fast processing**. It is fast enough to render on-demand in
+    most web applications without having to cache the output.
+
+*   **Thread safety**. You can run multiple parsers in different
+    goroutines without ill effect. There is no dependence on global
+    shared state.
+
+*   **Minimal dependencies**. Blackfriday only depends on standard
+    library packages in Go. The source code is pretty
+    self-contained, so it is easy to add to any project, including
+    Google App Engine projects.
+
+*   **Standards compliant**. Output successfully validates using the
+    W3C validation tool for HTML 4.01 and XHTML 1.0 Transitional.
+
+	[this is a link](https://github.com/kataras/iris) `
+
+// 10 seconds test
+// EXAMPLE: https://github.com/iris-contrib/examples/tree/master/cache_body
+func TestCacheBody(t *testing.T) {
+	iris.ResetDefault()
+	iris.Config.CacheGCDuration = time.Duration(2) * time.Second
+	iris.Config.IsDevelopment = true
+	defer iris.Close()
+	var i = 1
+	bodyHandler := func(ctx *iris.Context) {
+		if i%2 == 0 { // only for testing
+			ctx.SetStatusCode(iris.StatusNoContent)
+			i++
+			return
+		}
+		i++
+		ctx.Markdown(iris.StatusOK, testMarkdownContents)
+	}
+
+	expiration := time.Duration(3 * time.Second)
+
+	iris.Get("/", iris.Cache(bodyHandler, expiration))
+
+	e := httptest.New(iris.Default, t)
+
+	expectedBody := iris.SerializeToString("text/markdown", testMarkdownContents)
+
+	e.GET("/").Expect().Status(iris.StatusOK).Body().Equal(expectedBody)
+	e.GET("/").Expect().Status(iris.StatusOK).Body().Equal(expectedBody) // the cache still son the corrrect body so no StatusNoContent fires
+	time.Sleep(time.Duration(5) * time.Second)                           // 4 depends on the CacheGCDuration not the expiration
+
+	// the cache should be cleared and now i =  2 then it should run the iris.StatusNoContent  with empty body ( we don't use the EmitError)
+	e.GET("/").Expect().Status(iris.StatusNoContent).Body().Empty()
+	time.Sleep(time.Duration(5) * time.Second)
+
+	e.GET("/").Expect().Status(iris.StatusOK).Body().Equal(expectedBody)
+	e.GET("/").Expect().Status(iris.StatusOK).Body().Equal(expectedBody)
+}