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Description

#2755 only fixes the slice bounds out of range panic. Route params are not be handled correctly in test context. I can explain what happened.

When call CreateTestContext, it will call New function to create a Engine. The maxParams will be the default value 0.

Then allocateContext init the Params. The cap and len are both 0. params is the reference of Params.

Even if we add a route, it only incrs the maxParams value, it has not effect on the Context we created by CreateTestContext before. The condition will always be false.

How to reproduce

package main

import (
	"fmt"
	"net/http"
	"net/http/httptest"

	"github.com/gin-gonic/gin"
)

func main() {
	w := httptest.NewRecorder()
	ctx, engine := gin.CreateTestContext(w)
	engine.GET("/hello/:name", func(ctx *gin.Context) {
		fmt.Printf("Param name is %s\n", ctx.Param("name"))
		ctx.String(http.StatusOK, "Hello %s", ctx.Param("name"))
	})
	var err error
	ctx.Request, err = http.NewRequest(http.MethodGet, "/hello/world", nil)
	if err != nil {
		panic(err)
	}
	engine.HandleContext(ctx)
}

Expectations

Get following output after running the code.

[GIN-debug] GET    /hello/:name              --> main.main.func1 (1 handlers)
Param name is world

Actual result

[GIN-debug] GET    /hello/:name              --> main.main.func1 (1 handlers)
Param name is 

ctx.Param("name") returns a empty string.

Environment

• go version: go version go1.16 darwin/amd64
• gin version (or commit ref): v1.7.2-0.20210704023713-9c27053243cb
• operating system: macOs Big Sur 11.4, Darwin Kernel Version 20.5.0