hse-2026/homework/03-http-server/tests/contract_test.go

package hw3test

import (
	"bufio"
	"errors"
	"io"
	"net"
	"os"
	"path/filepath"
	"strings"
	"testing"
)

func TestContractResponseRejectsBadFraming(t *testing.T) {
	for _, tc := range []struct {
		name, response string
		valid          bool
	}{
		{"ok", "HTTP/1.1 200 OK\r\nConnection: close\r\nContent-Length: 4\r\n\r\ndata", true},
		{"short", "HTTP/1.1 200 OK\r\nConnection: close\r\nContent-Length: 5\r\n\r\ndata", false},
		{"long", "HTTP/1.1 200 OK\r\nConnection: close\r\nContent-Length: 3\r\n\r\ndata", false},
		{"no-close", "HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n", false},
		{"no-length", "HTTP/1.1 200 OK\r\nConnection: close\r\n\r\n", false},
		{"204", "HTTP/1.1 204 No Content\r\nConnection: close\r\n\r\n", true},
		{"204-length", "HTTP/1.1 204 No Content\r\nConnection: close\r\nContent-Length: 0\r\n\r\n", false},
		{"204-body", "HTTP/1.1 204 No Content\r\nConnection: close\r\n\r\nx", false},
		{"chunked", "HTTP/1.1 200 OK\r\nConnection: close\r\nTransfer-Encoding: chunked\r\n\r\n0\r\n\r\n", false},
	} {
		t.Run(tc.name, func(t *testing.T) {
			_, _, err := readContractResponse(bufio.NewReader(strings.NewReader(tc.response)), false)
			if (err == nil) != tc.valid {
				t.Fatalf("valid=%v, error=%v", tc.valid, err)
			}
		})
	}
}

type resetReader struct{}

func (resetReader) Read([]byte) (int, error) {
	return 0, &net.OpError{Op: "read", Net: "tcp", Err: errors.New("connection reset")}
}

func TestContractResponseAfterEarlyRejection(t *testing.T) {
	for _, tc := range []struct {
		name, body     string
		requestHasBody bool
		valid          bool
	}{
		{"complete error then reset", "error", true, true},
		{"reset without request body", "error", false, false},
		{"truncated error", "err", true, false},
		{"extra response byte", "error!", true, false},
	} {
		t.Run(tc.name, func(t *testing.T) {
			wire := "HTTP/1.1 409 Conflict\r\nConnection: close\r\nContent-Length: 5\r\n\r\n" + tc.body
			reader := bufio.NewReader(io.MultiReader(strings.NewReader(wire), resetReader{}))
			_, _, err := readContractResponse(reader, tc.requestHasBody)
			if (err == nil) != tc.valid {
				t.Fatalf("valid=%v, error=%v", tc.valid, err)
			}
		})
	}
}

func TestSnapshotDetectsErrorSideEffects(t *testing.T) {
	for _, mutation := range []string{"overwrite", "create", "delete", "mkdir"} {
		t.Run(mutation, func(t *testing.T) {
			root := t.TempDir()
			file := filepath.Join(root, "file")
			if err := os.WriteFile(file, []byte("before"), 0644); err != nil {
				t.Fatal(err)
			}
			before, err := snapshotTree(root)
			if err != nil {
				t.Fatal(err)
			}
			after, err := snapshotTree(root)
			if err != nil {
				t.Fatal(err)
			}
			if err := compareSnapshots(before, after); err != nil {
				t.Fatal(err)
			}
			switch mutation {
			case "overwrite":
				err = os.WriteFile(file, []byte("after!"), 0644)
			case "create":
				err = os.WriteFile(filepath.Join(root, "new"), nil, 0644)
			case "delete":
				err = os.Remove(file)
			case "mkdir":
				err = os.Mkdir(filepath.Join(root, "new"), 0755)
			}
			if err != nil {
				t.Fatal(err)
			}
			after, err = snapshotTree(root)
			if err != nil {
				t.Fatal(err)
			}
			if err := compareSnapshots(before, after); err == nil {
				t.Fatal("side effect was accepted")
			}
		})
	}
}

func TestMissingPathActionsAndRoot(t *testing.T) {
	env := &Env{RootDir: &EnvDir{Listing: map[string]EnvNode{"file": &EnvFile{}, "dir": &EnvDir{Listing: map[string]EnvNode{}}}}}
	opts := &RunOpts{ServerDomain: "localhost"}
	for _, tc := range []struct {
		method, path string
		status       int
	}{
		{"POST", "missing/new", 404}, {"POST", "file/new", 404},
		{"POST", "dir", 409}, {"PUT", "missing", 404}, {"PUT", "dir", 409}, {"DELETE", "missing", 404},
		{"POST", "/", 409}, {"PUT", "/", 409}, {"DELETE", "/", 403},
	} {
		q := Query{Method: tc.method, Path: tc.path, HostHeader: "LOCALHOST"}
		action, ok := q.Action(env, opts).(HttpErrorAction)
		if !ok || action.Status != tc.status {
			t.Errorf("%s %s: got %#v", tc.method, tc.path, q.Action(env, opts))
		}
	}
	q := Query{Method: "GET", Path: "", HostHeader: "LOCALHOST"}
	if _, ok := q.Action(env, opts).(GetDirAction); !ok {
		t.Fatal("root GET is not a listing")
	}
	for _, root := range []string{"", "/"} {
		for _, remove := range []bool{false, true} {
			q := Query{Method: "DELETE", Path: root, HostHeader: "localhost", RemoveDirectory: remove}
			action, ok := q.Action(env, opts).(HttpErrorAction)
			if !ok || action.Status != 403 {
				t.Fatalf("root DELETE with RemoveDirectory=%v: got %#v", remove, action)
			}
			q.HostHeader = "wrong.example"
			action, ok = q.Action(env, opts).(HttpErrorAction)
			if !ok || action.Status != 400 {
				t.Fatalf("Host must be checked before root DELETE: got %#v", action)
			}
		}
	}
}