使用/路径变量测试Chi路线

I'm having trouble testing my go-chi routes, specifically the route with path variables. Running the server with go run main.go works fine and requests to the route with the path variable behaves as expected.

When I run my tests for the routes, I always get the HTTP error: Unprocessable Entity. After logging out what's happening with articleID, it seems like the articleCtx isn't getting access to the path variable. Not sure if this means I need to use articleCtx in the tests, but I've tried ArticleCtx(http.HandlerFunc(GetArticleID)) and get the error:

panic: interface conversion: interface {} is nil, not *chi.Context [recovered] panic: interface conversion: interface {} is nil, not *chi.Context

Running the server: go run main.go

Testing the server: go test .

My source:

// main.go

package main

import (
    "context"
    "fmt"
    "net/http"
    "strconv"

    "github.com/go-chi/chi"
)

type ctxKey struct {
    name string
}

func main() {
    r := chi.NewRouter()

    r.Route("/articles", func(r chi.Router) {
        r.Route("/{articleID}", func(r chi.Router) {
            r.Use(ArticleCtx)
            r.Get("/", GetArticleID) // GET /articles/123
        })
    })

    http.ListenAndServe(":3333", r)
}

// ArticleCtx gives the routes using it access to the requested article ID in the path
func ArticleCtx(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        articleParam := chi.URLParam(r, "articleID")
        articleID, err := strconv.Atoi(articleParam)
        if err != nil {
            http.Error(w, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
            return
        }

        ctx := context.WithValue(r.Context(), ctxKey{"articleID"}, articleID)
        next.ServeHTTP(w, r.WithContext(ctx))
    })
}

// GetArticleID returns the article ID that the client requested
func GetArticleID(w http.ResponseWriter, r *http.Request) {
    ctx := r.Context()
    articleID, ok := ctx.Value(ctxKey{"articleID"}).(int)
    if !ok {
        http.Error(w, http.StatusText(http.StatusUnprocessableEntity), http.StatusUnprocessableEntity)
        return
    }

    w.Write([]byte(fmt.Sprintf("article ID:%d", articleID)))
}

// main_test.go

package main

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

func TestGetArticleID(t *testing.T) {
    tests := []struct {
        name           string
        rec            *httptest.ResponseRecorder
        req            *http.Request
        expectedBody   string
        expectedHeader string
    }{
        {
            name:         "OK_1",
            rec:          httptest.NewRecorder(),
            req:          httptest.NewRequest("GET", "/articles/1", nil),
            expectedBody: `article ID:1`,
        },
        {
            name:         "OK_100",
            rec:          httptest.NewRecorder(),
            req:          httptest.NewRequest("GET", "/articles/100", nil),
            expectedBody: `article ID:100`,
        },
        {
            name:         "BAD_REQUEST",
            rec:          httptest.NewRecorder(),
            req:          httptest.NewRequest("PUT", "/articles/bad", nil),
            expectedBody: fmt.Sprintf("%s
", http.StatusText(http.StatusBadRequest)),
        },
    }

    for _, test := range tests {
        t.Run(test.name, func(t *testing.T) {
            ArticleCtx(http.HandlerFunc(GetArticleID)).ServeHTTP(test.rec, test.req)

            if test.expectedBody != test.rec.Body.String() {
                t.Errorf("Got: \t\t%s
\tExpected: \t%s
", test.rec.Body.String(), test.expectedBody)
            }
        })
    }
}

Not sure how to continue with this. Any ideas? I was wondering if there was an answer in net/http/httptest about using context with tests but didn't see anything.

Also pretty new go Go (and the context package), so any code review / best practice comments are greatly appreciated :)