func HTTPBodyNotContains(t TestingT, handler http.HandlerFunc, mode, url string, values url.Values, str interface{}) bool {
	body := HttpBody(handler, mode, url, values)
	contains := strings.Contains(body, fmt.Sprint(str))
	if contains {
		Fail(t, "Expected response body for %s to NOT contain \"%s\" but found \"%s\"", url+"?"+values.Encode(), str, body)
	}
	return !contains
}
HTTPBodyNotContains asserts that a specified handler returns a
body that does not contain a string.

assert.HTTPBodyNotContains(t, myHandler, "www.google.com", nil, "I'm Feeling Lucky")

Returns whether the assertion was successful (true) or not (false).
package assert
import (
	"fmt"
	"net/http"
	"net/http/httptest"
	"net/url"
	"strings"
)
func httpCode(handler http.HandlerFunc, mode, url string, values url.Values) int {
	w := httptest.NewRecorder()
	req, err := http.NewRequest(mode, url+"?"+values.Encode(), nil)
	if err != nil {
		return -1
	}
	handler(w, req)
	return w.Code
}
func HTTPSuccess(t TestingT, handler http.HandlerFunc, mode, url string, values url.Values) bool {
	code := httpCode(handler, mode, url, values)
	if code == -1 {
		return false
	}
	return code >= http.StatusOK && code <= http.StatusPartialContent
}
func HTTPRedirect(t TestingT, handler http.HandlerFunc, mode, url string, values url.Values) bool {
	code := httpCode(handler, mode, url, values)
	if code == -1 {
		return false
	}
	return code >= http.StatusMultipleChoices && code <= http.StatusTemporaryRedirect
}
func HTTPError(t TestingT, handler http.HandlerFunc, mode, url string, values url.Values) bool {
	code := httpCode(handler, mode, url, values)
	if code == -1 {
		return false
	}
	return code >= http.StatusBadRequest
}
func HttpBody(handler http.HandlerFunc, mode, url string, values url.Values) string {
	w := httptest.NewRecorder()
	req, err := http.NewRequest(mode, url+"?"+values.Encode(), nil)
	if err != nil {
		return ""
	}
	handler(w, req)
	return w.Body.String()
}
func HTTPBodyContains(t TestingT, handler http.HandlerFunc, mode, url string, values url.Values, str interface{}) bool {
	body := HttpBody(handler, mode, url, values)
	contains := strings.Contains(body, fmt.Sprint(str))
	if !contains {
		Fail(t, fmt.Sprintf("Expected response body for \"%s\" to contain \"%s\" but found \"%s\"", url+"?"+values.Encode(), str, body))
	}
	return contains
}