package main

...

func ping(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("OK"))
}

package main

import (
    "bytes"
    "io"
    "net/http"
    "net/http/httptest"
    "testing"

    "snippetbox.alexedwards.net/internal/assert"
)

func TestPing(t *testing.T) {
    // Initialize a new httptest.ResponseRecorder.
    rr := httptest.NewRecorder()

    // Initialize a new dummy http.Request.
    r, err := http.NewRequest(http.MethodGet, "/", nil)
    if err != nil {
        t.Fatal(err)
    }

    // Call the ping handler function, passing in the
    // httptest.ResponseRecorder and http.Request.
    ping(rr, r)

    // Call the Result() method on the http.ResponseRecorder to get the
    // http.Response generated by the ping handler.
    rs := rr.Result()

    // Check that the status code written by the ping handler was 200.
    assert.Equal(t, rs.StatusCode, http.StatusOK)
   
    // And we can check that the response body written by the ping handler
    // equals "OK".
    defer rs.Body.Close()
    body, err := io.ReadAll(rs.Body)
    if err != nil {
        t.Fatal(err)
    }
    body = bytes.TrimSpace(body)

    assert.Equal(t, string(body), "OK")
}

package main

import (
    "bytes"
    "io"
    "net/http"
    "net/http/httptest"
    "testing"

    "snippetbox.alexedwards.net/internal/assert"
)

func TestCommonHeaders(t *testing.T) {
    // Initialize a new httptest.ResponseRecorder and dummy http.Request.
    rr := httptest.NewRecorder()

    r, err := http.NewRequest(http.MethodGet, "/", nil)
    if err != nil {
        t.Fatal(err)
    }

    // Create a mock HTTP handler that we can pass to our commonHeaders
    // middleware, which writes a 200 status code and an "OK" response body.
    next := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        w.Write([]byte("OK"))
    })

    // Pass the mock HTTP handler to our commonHeaders middleware. Because
    // commonHeaders *returns* a http.Handler we can call its ServeHTTP()
    // method, passing in the http.ResponseRecorder and dummy http.Request to
    // execute it.
    commonHeaders(next).ServeHTTP(rr, r)

    // Call the Result() method on the http.ResponseRecorder to get the results
    // of the test.
    rs := rr.Result()

    // Check that the middleware has correctly set the Content-Security-Policy
    // header on the response.
    expectedValue := "default-src 'self'; style-src 'self' fonts.googleapis.com; font-src fonts.gstatic.com"
    assert.Equal(t, rs.Header.Get("Content-Security-Policy"), expectedValue)

    // Check that the middleware has correctly set the Referrer-Policy
    // header on the response.
    expectedValue = "origin-when-cross-origin"
    assert.Equal(t, rs.Header.Get("Referrer-Policy"), expectedValue)

    // Check that the middleware has correctly set the X-Content-Type-Options
    // header on the response.
    expectedValue = "nosniff"
    assert.Equal(t, rs.Header.Get("X-Content-Type-Options"), expectedValue)

    // Check that the middleware has correctly set the X-Frame-Options header
    // on the response.
    expectedValue = "deny"
    assert.Equal(t, rs.Header.Get("X-Frame-Options"), expectedValue)

    // Check that the middleware has correctly set the X-XSS-Protection header
    // on the response
    expectedValue = "0"
    assert.Equal(t, rs.Header.Get("X-XSS-Protection"), expectedValue)

    // Check that the middleware has correctly set the Server header on the 
    // response.
    expectedValue = "Go"
    assert.Equal(t, rs.Header.Get("Server"), expectedValue)

    // Check that the middleware has correctly called the next handler in line
    // and the response status code and body are as expected.
    assert.Equal(t, rs.StatusCode, http.StatusOK)

    defer rs.Body.Close()
    body, err := io.ReadAll(rs.Body)
    if err != nil {
        t.Fatal(err)
    }
    body = bytes.TrimSpace(body)
    
    assert.Equal(t, string(body), "OK")
}