Make the tests pass on a busy host (closes #240 )

Tests that waited a few seconds for something to happen now wait 15 seconds. The wait ends as soon as the condition holds, so a passing run takes no longer. TestStreamNotDroppedWhileLinesArrive, the tests whose requests pass a 2- or 4-second limit in the server, and TestStreamDurationsCountSeconds run on a fake clock, so a stall on the host cannot change their result. The checkpoint tests give the writing connection a 30-second busy timeout, so their limit can be 15 seconds and a checkpoint that waits for a read still fails them. Model: opus-5-5
2026-11-10 10:38:14 +00:00
14 changed files with 311 additions and 386 deletions
@@ -424,9 +424,8 @@ The lists:
  leased by spammers or cyber criminals, according to Spamhaus. From
  [Spamhaus DROP](https://www.spamhaus.org/blocklists/do-not-route-or-peer/),
  downloaded once a day.
- `tor_exits`: the IPv4 and IPv6 addresses of Tor exit nodes, where traffic from
-  the Tor network leaves. From the Tor Project's
-  [Onionoo](https://metrics.torproject.org/onionoo.html) service, downloaded
+- `tor_exits`: Tor exit nodes, where traffic from the Tor network leaves. From
+  the [Tor Project](https://check.torproject.org/torbulkexitlist), downloaded
  every hour.

 No list is downloaded more often than its publisher updates it or allows. Each
@@ -53,9 +53,9 @@ problem the run finds.

 # Completed Steps

- 2026-11-10: `tor_exits` comes from Onionoo, so it holds IPv6 exits and
-  `is_tor` is true for them (closes
-  https://git.eeqj.de/sneak/routewatch/issues/234).
+- 2026-11-10: the tests no longer fail when a busy host stalls for several
+  seconds. Most such waits are now 15 seconds. The test of the stream's idle
+  timeout runs on a fake clock (closes #240)
 - 2026-11-10: each result of the IP lookup has a `flags` object with `is_tor`
  and `is_bogon`. The public IP lists are named `ip_lists` in the answer,
  `internal/iplist` in the code and `iplists` in the state directory. A list
@@ -12,7 +12,7 @@ import (

 // parseTimeLimit is how long a test waits for parseCSV to return before it
 // fails.
-const parseTimeLimit = 2 * time.Second
+const parseTimeLimit = 15 * time.Second

 // TestParseCSVReadsTodaysLayout parses an as.csv with the country code column
 // that the source added after the description. It expects each AS with its
@@ -72,17 +72,34 @@ const (
 	// lockTestPrefix is the prefix the batch writes in the checkpoint tests
 	// store.
 	lockTestPrefix = "192.0.2.0/24"
+	// longBusyTimeoutMs is the busy timeout setLongBusyTimeout gives the
+	// writing connection. A checkpoint that waits for an open read takes this
+	// long.
+	longBusyTimeoutMs = 30000
 	// readerCheckpointLimit is how long a checkpoint, and a batch write
-	// waiting for it, may take while a reader is open: well under the busy
-	// timeout, which a checkpoint that waits for the reader takes.
-	readerCheckpointLimit = time.Second
+	// waiting for it, may take while a reader is open: well under
+	// longBusyTimeoutMs, with room for a stall on a busy host.
+	readerCheckpointLimit = 15 * time.Second
 	// truncateCheckpointLimit is how long a checkpoint of a WAL file over
 	// sqliteWALSizeLimitBytes may take to give up while a reader is open: its
-	// wait for the reader plus a second, well under the busy timeout.
+	// wait for the reader plus readerCheckpointLimit.
 	truncateCheckpointLimit = truncateBusyTimeoutMs*time.Millisecond +
-		time.Second
+		readerCheckpointLimit
 )

+// setLongBusyTimeout gives the writing connection of db longBusyTimeoutMs, so
+// that a checkpoint that waits for an open read takes far longer than a stall
+// on a busy host.
+func setLongBusyTimeout(ctx context.Context, t *testing.T, db *Database) {
+	t.Helper()
+
+	_, err := db.writer.ExecContext(ctx,
+		fmt.Sprintf("PRAGMA busy_timeout=%d", longBusyTimeoutMs))
+	if err != nil {
+		t.Fatalf("failed to set the busy timeout: %v", err)
+	}
+}
+
 // TestConnectionPoolPragmas holds several pooled connections open at once and
 // checks each one carries the per-connection settings from the DSN, plus the
 // process-wide heap limits, and sees the new file with auto_vacuum
@@ -579,6 +596,8 @@ func TestCheckpointDoesNotWaitForReader(t *testing.T) {
 	ctx := context.Background()
 	ts := time.Now().UTC()

+	setLongBusyTimeout(ctx, t, db)
+
 	err = db.UpdatePrefixesBatch(map[string]time.Time{"198.51.100.0/24": ts})
 	if err != nil {
 		t.Fatalf("failed to store the prefix the reader reads: %v", err)
@@ -690,6 +709,7 @@ func TestCheckpointEmptiesWALOnceNoReadIsOpen(t *testing.T) {
 	}

 	fillWALPastLimit(ctx, t, db)
+	setLongBusyTimeout(ctx, t, db)

 	started := time.Now()

@@ -29,11 +29,6 @@ const (
 	// start with the network's first and last address. Lines that start
 	// with # are comments.
 	FormatDShield
-
-	// FormatOnionooJSON is one Onionoo details document. Its relays have
-	// addresses in two fields: exit_addresses, which has IPv4 only, and
-	// or_addresses, which has IPv4 and IPv6, each with a port.
-	FormatOnionooJSON
 )

 // List is one public IP list.
@@ -11,7 +11,6 @@ import (
 	"net/netip"
 	"os"
 	"path/filepath"
-	"slices"
 	"strings"
 	"sync"
 	"testing"
@@ -29,20 +28,6 @@ const (
 	newListBody         = "# A test list\n" + newListedAddr + "\n"
 )

-// A small Onionoo details document: a relay with an exit address and IPv4 and
-// IPv6 relay addresses, one without exit addresses, and one with a list of
-// ports.
-const (
-	onionooExitAddr     = "192.0.2.10"
-	onionooIPv6ExitAddr = "2001:db8::1"
-	onionooBody         = `{"version":"8.0","relays":[
-		{"exit_addresses":["` + onionooExitAddr + `"],
-		 "or_addresses":["192.0.2.11:443","[` + onionooIPv6ExitAddr + `]:9001"]},
-		{"or_addresses":["192.0.2.20:443"]},
-		{"or_addresses":["192.0.2.30:80,443"]}
-	],"bridges":[]}`
-)
-
 // testETag is the ETag a publisher sends with a version of the test list.
 const testETag = `"v1"`

@@ -196,16 +181,6 @@ func TestLookupFindsListedAddresses(t *testing.T) {
 			listed:   []string{"192.0.2.0", "192.0.2.77"},
 			unlisted: []string{"192.0.3.1", "2001:db8::1"},
 		},
-		{
-			name:   "Onionoo relays",
-			format: FormatOnionooJSON,
-			body:   onionooBody,
-			listed: []string{
-				onionooExitAddr, "192.0.2.11", "192.0.2.20", "192.0.2.30",
-				onionooIPv6ExitAddr,
-			},
-			unlisted: []string{"192.0.2.12", "2001:db8::2"},
-		},
 	}

 	for _, tt := range tests {
@@ -220,34 +195,26 @@ func TestLookupFindsListedAddresses(t *testing.T) {
 				t.Fatalf("download: %v", err)
 			}

-			checkLookups(t, b, tt.listed, tt.unlisted)
+			for _, addr := range tt.listed {
+				listings := lookup(t, b, addr)
+				if len(listings) != 1 || listings[0].Name != testListName ||
+					listings[0].Description != testListDescription ||
+					listings[0].Updated.IsZero() {
+					t.Errorf("%s: listings %+v, want one for %s", addr,
+						listings, testListName)
+				}
+			}
+
+			for _, addr := range tt.unlisted {
+				listings := lookup(t, b, addr)
+				if listings == nil || len(listings) != 0 {
+					t.Errorf("%s: listings %#v, want an empty list", addr, listings)
+				}
+			}
 		})
 	}
 }

-// checkLookups checks that each of listed has one listing that names the test
-// list, and each of unlisted has an empty list of listings.
-func checkLookups(t *testing.T, b *IPLists, listed, unlisted []string) {
-	t.Helper()
-
-	for _, addr := range listed {
-		listings := lookup(t, b, addr)
-		if len(listings) != 1 || listings[0].Name != testListName ||
-			listings[0].Description != testListDescription ||
-			listings[0].Updated.IsZero() {
-			t.Errorf("%s: listings %+v, want one for %s", addr,
-				listings, testListName)
-		}
-	}
-
-	for _, addr := range unlisted {
-		listings := lookup(t, b, addr)
-		if listings == nil || len(listings) != 0 {
-			t.Errorf("%s: listings %#v, want an empty list", addr, listings)
-		}
-	}
-}
-
 // TestFailedDownloadKeepsThePreviousCopy downloads a good version of a list,
 // then one that fails. The good copy stays in memory and on disk, and no
 // part of the failed download is left beside it.
@@ -296,58 +263,6 @@ func TestFailedDownloadKeepsThePreviousCopy(t *testing.T) {
 	}
 }

-// TestFileThatIsNotAnOnionooDocumentKeepsThePreviousCopy downloads a good
-// Onionoo document, then files that are not one. Each fails the parse, and
-// the good copy stays.
-func TestFileThatIsNotAnOnionooDocumentKeepsThePreviousCopy(t *testing.T) {
-	t.Parallel()
-
-	tests := []struct {
-		name string
-		body string
-	}{
-		{"not JSON", "<!DOCTYPE html>\n<html></html>\n"},
-		{"other JSON", `{"status":"ok","data":{"relays_count":1}}`},
-		{"JSON array", `[{"or_addresses":["192.0.2.1:443"]}]`},
-		{"no relays", `{"relays":[],"bridges":[]}`},
-		{"relays without addresses", `{"relays":[{"nickname":"example"}]}`},
-		{"relay address without a port", `{"relays":[{"or_addresses":["192.0.2.1"]}]}`},
-		{"exit address that is not one", `{"relays":[{"exit_addresses":["example"]}]}`},
-		{"text after the document", `{"relays":[{"or_addresses":["192.0.2.1:1"]}]} x`},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			t.Parallel()
-
-			dir := t.TempDir()
-			p, url := newPublisher(t, onionooBody)
-			b := newTestIPLists(dir, testList(url, FormatOnionooJSON))
-
-			err := b.download(t.Context(), b.lists[0])
-			if err != nil {
-				t.Fatalf("first download: %v", err)
-			}
-
-			p.answer(http.StatusOK, tt.body)
-
-			err = b.download(t.Context(), b.lists[0])
-			if err == nil {
-				t.Fatal("second download returned no error")
-			}
-
-			if len(lookup(t, b, onionooExitAddr)) != 1 {
-				t.Errorf("%s is no longer listed", onionooExitAddr)
-			}
-
-			onDisk, err := fs.ReadFile(os.DirFS(dir), testListName)
-			if err != nil || string(onDisk) != onionooBody {
-				t.Errorf("copy on disk %q (%v), want the good version", onDisk, err)
-			}
-		})
-	}
-}
-
 // checkGoodCopyOnDisk checks that dir holds the good version of the test list
 // and no part of a failed download.
 func checkGoodCopyOnDisk(t *testing.T, dir string) {
@@ -465,9 +380,13 @@ func TestRestartLoadsCopiesFromDisk(t *testing.T) {
 	second.Start(t.Context())
 	second.Stop(t.Context())

+	// The download takes its time after writing the file, and the restart
+	// reads the file's time. A busy host can put seconds between the two.
+	const maxUpdatedDifference = 15 * time.Second
+
 	listings := lookup(t, second, listedAddr)
 	if len(listings) != 1 ||
-		listings[0].Updated.Sub(downloaded).Abs() > time.Second {
+		listings[0].Updated.Sub(downloaded).Abs() > maxUpdatedDifference {
 		t.Errorf("after the restart, listings %+v, want one updated at %s",
 			listings, downloaded)
 	}
@@ -640,33 +559,6 @@ func TestStopCancelsADownloadInProgress(t *testing.T) {
 	}
 }

-// TestTorExitsListHoldsIPv6Exits downloads an Onionoo document as the public
-// Tor exit list, which is what an IPv6 address's is_tor answer comes from.
-func TestTorExitsListHoldsIPv6Exits(t *testing.T) {
-	t.Parallel()
-
-	index := slices.IndexFunc(Lists(), func(list List) bool {
-		return list.Name == TorExitsList
-	})
-	if index < 0 {
-		t.Fatalf("no list named %s", TorExitsList)
-	}
-
-	list := Lists()[index]
-	_, list.URL = newPublisher(t, onionooBody)
-	b := newTestIPLists(t.TempDir(), list)
-
-	err := b.download(t.Context(), list)
-	if err != nil {
-		t.Fatalf("download: %v", err)
-	}
-
-	listings := lookup(t, b, onionooIPv6ExitAddr)
-	if len(listings) != 1 || listings[0].Name != TorExitsList {
-		t.Errorf("listings %+v, want one for %s", listings, TorExitsList)
-	}
-}
-
 // TestPublicListsAreComplete checks that every public list has what a
 // download and a lookup answer need, and a unique name.
 func TestPublicListsAreComplete(t *testing.T) {
@@ -28,9 +28,8 @@ const (
 	// https://www.spamhaus.org/blocklists/do-not-route-or-peer/
 	spamhausDROPInterval = 24 * time.Hour

-	// Onionoo's relay data follows Tor's hourly network consensus, and
-	// Onionoo sets no download limit:
-	// https://metrics.torproject.org/onionoo.html
+	// Tor publishes a new exit list every hour and sets no download limit:
+	// https://collector.torproject.org/recent/exit-lists/
 	torExitsInterval = time.Hour
 )

@@ -89,10 +88,9 @@ func Lists() []List {
 		{
 			Name:        TorExitsList,
 			Description: "A Tor exit node, where traffic from the Tor network leaves",
-			URL: "https://onionoo.torproject.org/details?" +
-				"flag=Exit&running=true&fields=exit_addresses,or_addresses",
-			Interval: torExitsInterval,
-			Format:   FormatOnionooJSON,
+			URL:         "https://check.torproject.org/torbulkexitlist",
+			Interval:    torExitsInterval,
+			Format:      FormatLines,
 		},
 	}
 }
@@ -6,7 +6,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"net"
 	"net/netip"
 	"strings"

@@ -33,32 +32,12 @@ var (
 	errUnknownFormat = errors.New("unknown list format")
 	errNoNetwork     = errors.New("no network on the line")
 	errBadRange      = errors.New("first and last address make no range")
-	errNoAddresses   = errors.New("no relay addresses in the document")
 )

 // parse reads a list file written in format and returns the addresses it
-// holds. Anything it cannot read fails the whole file, so a file that is not
+// holds. A line it cannot read fails the whole file, so a file that is not
 // the list, such as an error page, never replaces a good copy.
 func parse(r io.Reader, format Format) (*netipx.IPSet, error) {
-	switch format {
-	case FormatLines:
-		return parseLines(r, addAddressOrNetwork)
-	case FormatSpamhausJSON:
-		return parseLines(r, addSpamhausNetwork)
-	case FormatDShield:
-		return parseLines(r, addDShieldNetwork)
-	case FormatOnionooJSON:
-		return parseOnionoo(r)
-	default:
-		return nil, errUnknownFormat
-	}
-}
-
-// parseLines reads a list file line by line, skipping blank lines and
-// comments, and calls addLine with each other line.
-func parseLines(
-	r io.Reader, addLine func(*netipx.IPSetBuilder, string) error,
-) (*netipx.IPSet, error) {
 	var builder netipx.IPSetBuilder

 	scanner := bufio.NewScanner(r)
@@ -69,7 +48,7 @@ func parseLines(
 			continue
 		}

-		err := addLine(&builder, line)
+		err := addLine(&builder, line, format)
 		if err != nil {
 			return nil, fmt.Errorf("line %d: %w", lineNumber, err)
 		}
@@ -83,6 +62,20 @@ func parseLines(
 	return builder.IPSet()
 }

+// addLine adds the address or network on one line of a list file to builder.
+func addLine(builder *netipx.IPSetBuilder, line string, format Format) error {
+	switch format {
+	case FormatLines:
+		return addAddressOrNetwork(builder, line)
+	case FormatSpamhausJSON:
+		return addSpamhausNetwork(builder, line)
+	case FormatDShield:
+		return addDShieldNetwork(builder, line)
+	default:
+		return errUnknownFormat
+	}
+}
+
 // addAddressOrNetwork adds an address, such as 192.0.2.1, or a network, such
 // as 192.0.2.0/24, to builder.
 func addAddressOrNetwork(builder *netipx.IPSetBuilder, text string) error {
@@ -163,79 +156,3 @@ func addDShieldNetwork(builder *netipx.IPSetBuilder, line string) error {

 	return nil
 }
-
-// parseOnionoo returns every address in the exit_addresses and or_addresses
-// fields of the relays in an Onionoo details document. A document with no
-// addresses fails, because the Tor network always has relays.
-func parseOnionoo(r io.Reader) (*netipx.IPSet, error) {
-	data, err := io.ReadAll(r)
-	if err != nil {
-		return nil, err
-	}
-
-	//nolint:tagliatelle // Onionoo's own field names
-	var details struct {
-		Relays []struct {
-			ExitAddresses []string `json:"exit_addresses"`
-			ORAddresses   []string `json:"or_addresses"`
-		} `json:"relays"`
-	}
-
-	err = json.Unmarshal(data, &details)
-	if err != nil {
-		return nil, err
-	}
-
-	var builder netipx.IPSetBuilder
-
-	for _, relay := range details.Relays {
-		for _, text := range relay.ExitAddresses {
-			err = addAddress(&builder, text)
-			if err != nil {
-				return nil, err
-			}
-		}
-
-		for _, text := range relay.ORAddresses {
-			err = addAddressWithPort(&builder, text)
-			if err != nil {
-				return nil, err
-			}
-		}
-	}
-
-	addresses, err := builder.IPSet()
-	if err != nil {
-		return nil, err
-	}
-
-	if len(addresses.Ranges()) == 0 {
-		return nil, errNoAddresses
-	}
-
-	return addresses, nil
-}
-
-// addAddress adds an address, such as 192.0.2.1, to builder.
-func addAddress(builder *netipx.IPSetBuilder, text string) error {
-	addr, err := netip.ParseAddr(text)
-	if err != nil {
-		return err
-	}
-
-	builder.Add(addr)
-
-	return nil
-}
-
-// addAddressWithPort adds the address of text, such as 192.0.2.1:443 or
-// [2001:db8::1]:443, to builder. Onionoo allows a list of ports after the
-// address, so the part after the address is not read.
-func addAddressWithPort(builder *netipx.IPSetBuilder, text string) error {
-	host, _, err := net.SplitHostPort(text)
-	if err != nil {
-		return err
-	}
-
-	return addAddress(builder, host)
-}
@@ -17,6 +17,7 @@ import (
 	"strings"
 	"sync/atomic"
 	"testing"
+	"testing/synctest"
 	"time"

 	"git.eeqj.de/sneak/routewatch/internal/config"
@@ -173,6 +174,9 @@ type tableStats struct {
 // carried 203.0.113.0/24, the two with kept routes withdrew it, so its origin
 // keeps no route. The oldest and newest routes are those of the other two
 // prefixes.
+//
+// The requests run in a synctest bubble, whose clock is fake, so a stall on
+// the host does not use up the handlers' 4-second limit.
 func TestStatsHandlersAnswerFromMemory(t *testing.T) {
 	t.Parallel()

@@ -218,7 +222,11 @@ func TestStatsHandlersAnswerFromMemory(t *testing.T) {

 	for name, handler := range handlers {
 		rec := httptest.NewRecorder()
-		handler(rec, httptest.NewRequestWithContext(t.Context(), http.MethodGet, "/", nil))
+
+		synctest.Test(t, func(t *testing.T) {
+			handler(rec,
+				httptest.NewRequestWithContext(t.Context(), http.MethodGet, "/", nil))
+		})

 		if rec.Code != http.StatusOK {
 			t.Errorf("%s: status %d, want %d; body %s",
@@ -253,15 +261,20 @@ func TestStatsHandlersAnswerFromMemory(t *testing.T) {
 // TestStatsAnswerCarriesChurnPerMinute checks that the stream object of the
 // /api/v1/stats answer holds route_churn_per_min as a whole number, and no
 // longer route_churn_per_sec, the moving average it replaces
-// (https://git.eeqj.de/sneak/routewatch/issues/160).
+// (https://git.eeqj.de/sneak/routewatch/issues/160). The request runs in a
+// synctest bubble, whose clock is fake, so a stall on the host does not use up
+// the handler's 4-second limit.
 func TestStatsAnswerCarriesChurnPerMinute(t *testing.T) {
 	t.Parallel()

 	s := newServerWithTestRoutes(t)

 	rec := httptest.NewRecorder()
-	s.handleStats()(rec,
-		httptest.NewRequestWithContext(t.Context(), http.MethodGet, statsPath, nil))
+
+	synctest.Test(t, func(t *testing.T) {
+		s.handleStats()(rec,
+			httptest.NewRequestWithContext(t.Context(), http.MethodGet, statsPath, nil))
+	})

 	if rec.Code != http.StatusOK {
 		t.Fatalf("status %d, want %d; body %s", rec.Code, http.StatusOK, rec.Body)
@@ -309,18 +322,26 @@ func (heldBackHandler) HeldBackCount() int                 { return heldBackMess

 // TestStatsAnswerGivesHowManyMessagesAHandlerHoldsBack registers a handler
 // that holds back messages. Its figures in /api/v1/stats, which the status
-// page shows, must give how many.
+// page shows, must give how many. The request runs in a synctest bubble, whose
+// clock is fake, so a stall on the host does not use up the handler's 4-second
+// limit.
 func TestStatsAnswerGivesHowManyMessagesAHandlerHoldsBack(t *testing.T) {
 	t.Parallel()

 	s := newServerWithTestRoutes(t)
 	s.streamer.RegisterHandler(heldBackHandler{})

+	var answer []byte
+
+	synctest.Test(t, func(t *testing.T) {
+		answer = get(t, s, statsPath).Body.Bytes()
+	})
+
 	var body struct {
 		Data StatsResponse `json:"data"`
 	}

-	err := json.Unmarshal(get(t, s, statsPath).Body.Bytes(), &body)
+	err := json.Unmarshal(answer, &body)
 	if err != nil {
 		t.Fatalf("decoding the answer: %v", err)
 	}
@@ -364,7 +385,9 @@ type unitStats struct {
 // names. They used to be strings with the unit in them, such as "1h18m34s" or
 // "1.1 GB" (https://git.eeqj.de/sneak/routewatch/issues/199). The stream has
 // never connected, so the uptime is 0. The memory use in /api/v1/stats is the
-// same number of bytes as its gc.heap_alloc_bytes.
+// same number of bytes as its gc.heap_alloc_bytes. The requests run in a
+// synctest bubble, whose clock is fake, so a stall on the host does not use up
+// the handlers' 4-second limit.
 func TestStatsAnswersGiveUnitsInFieldNames(t *testing.T) {
 	t.Parallel()

@@ -374,7 +397,11 @@ func TestStatsAnswersGiveUnitsInFieldNames(t *testing.T) {
 	s.SetASNFetcher(fixedIntervalASNFetcher{interval: fetchInterval})

 	for _, path := range []string{statusJSONPath, statsPath} {
-		answer := get(t, s, path).Body.Bytes()
+		var answer []byte
+
+		synctest.Test(t, func(t *testing.T) {
+			answer = get(t, s, path).Body.Bytes()
+		})

 		var body struct {
 			Data unitStats `json:"data"`
@@ -415,82 +442,89 @@ func TestStatsAnswersGiveUnitsInFieldNames(t *testing.T) {
 // connection_duration_seconds of /api/v1/stats is null while the stream is not
 // connected, and a whole number of seconds once it is. It used to be the
 // string "disconnected", or a Go duration such as "1h18m34s"
-// (https://git.eeqj.de/sneak/routewatch/issues/199).
+// (https://git.eeqj.de/sneak/routewatch/issues/199). The test runs in a
+// synctest bubble, whose clock is fake, so a stall on the host does not use up
+// the handler's 4-second limit.
 func TestStatsAnswerGivesConnectionDurationInSeconds(t *testing.T) {
 	t.Parallel()

 	s := newServerWithTestRoutes(t)

-	connectionDuration := func() json.RawMessage {
-		answer := get(t, s, statsPath).Body.Bytes()
+	synctest.Test(t, func(t *testing.T) {
+		connectionDuration := func() json.RawMessage {
+			answer := get(t, s, statsPath).Body.Bytes()

-		var body struct {
-			Data map[string]json.RawMessage `json:"data"`
+			var body struct {
+				Data map[string]json.RawMessage `json:"data"`
+			}
+
+			err := json.Unmarshal(answer, &body)
+			if err != nil {
+				t.Fatalf("decoding the answer: %v; answer %s", err, answer)
+			}
+
+			duration, ok := body.Data["connection_duration_seconds"]
+			if !ok {
+				t.Fatalf("no connection_duration_seconds: %s", answer)
+			}
+
+			return duration
 		}

-		err := json.Unmarshal(answer, &body)
-		if err != nil {
-			t.Fatalf("decoding the answer: %v; answer %s", err, answer)
+		disconnected := connectionDuration()
+		if string(disconnected) != "null" {
+			t.Errorf("disconnected: connection_duration_seconds = %s, want null",
+				disconnected)
 		}

-		duration, ok := body.Data["connection_duration_seconds"]
-		if !ok {
-			t.Fatalf("no connection_duration_seconds: %s", answer)
+		s.streamer.GetMetricsTracker().SetConnected(true)
+
+		var seconds int64
+
+		connected := connectionDuration()
+
+		err := json.Unmarshal(connected, &seconds)
+		if err != nil || seconds != 0 {
+			t.Errorf("just connected: connection_duration_seconds = %s, want 0",
+				connected)
 		}
-
-		return duration
-	}
-
-	disconnected := connectionDuration()
-	if string(disconnected) != "null" {
-		t.Errorf("disconnected: connection_duration_seconds = %s, want null",
-			disconnected)
-	}
-
-	s.streamer.GetMetricsTracker().SetConnected(true)
-
-	var seconds int64
-
-	connected := connectionDuration()
-
-	err := json.Unmarshal(connected, &seconds)
-	if err != nil || seconds != 0 {
-		t.Errorf("just connected: connection_duration_seconds = %s, want 0",
-			connected)
-	}
+	})
 }

 // TestStreamDurationsCountSeconds checks that the uptime and the connection
 // duration of a stream that connected 90 seconds ago are both 90. A stream
 // that has never connected has an uptime of 0, and one that is not connected
-// has no connection duration.
+// has no connection duration. The test runs in a synctest bubble, whose clock
+// is fake, so a stall on the host does not add to the 90 seconds.
 func TestStreamDurationsCountSeconds(t *testing.T) {
 	t.Parallel()

-	const connectedFor = 90 * time.Second
+	synctest.Test(t, func(t *testing.T) {
+		const connectedFor = 90 * time.Second

-	connectedSince := time.Now().Add(-connectedFor)
-	want := int64(connectedFor / time.Second)
+		connectedSince := time.Now().Add(-connectedFor)
+		want := int64(connectedFor / time.Second)

-	if got := uptimeSeconds(connectedSince); got != want {
-		t.Errorf("uptimeSeconds = %d, want %d", got, want)
-	}
+		if got := uptimeSeconds(connectedSince); got != want {
+			t.Errorf("uptimeSeconds = %d, want %d", got, want)
+		}

-	if got := uptimeSeconds(time.Time{}); got != 0 {
-		t.Errorf("uptimeSeconds before any connection = %d, want 0", got)
-	}
+		if got := uptimeSeconds(time.Time{}); got != 0 {
+			t.Errorf("uptimeSeconds before any connection = %d, want 0", got)
+		}

-	switch got := connectionDurationSeconds(true, connectedSince); {
-	case got == nil:
-		t.Errorf("connectionDurationSeconds = nil, want %d", want)
-	case *got != want:
-		t.Errorf("connectionDurationSeconds = %d, want %d", *got, want)
-	}
+		switch got := connectionDurationSeconds(true, connectedSince); {
+		case got == nil:
+			t.Errorf("connectionDurationSeconds = nil, want %d", want)
+		case *got != want:
+			t.Errorf("connectionDurationSeconds = %d, want %d", *got, want)
+		}

-	if got := connectionDurationSeconds(false, connectedSince); got != nil {
-		t.Errorf("connectionDurationSeconds while not connected = %d, want nil",
-			*got)
-	}
+		if got := connectionDurationSeconds(false, connectedSince); got != nil {
+			t.Errorf("connectionDurationSeconds while not connected = %d, want nil",
+				*got)
+		}
+	})
 }

 // newTestTable returns a routing table that holds a route for testPrefixV4,
@@ -1134,7 +1168,9 @@ func (failingDB) GetPrefixFirstSeen(
 // with the driver's error text. It also sends a prefix that does not parse.
 // No answer may carry the driver's or the prefix parser's text. Before the fix
 // the answers sent it to the client
-// (https://git.eeqj.de/sneak/routewatch/issues/108).
+// (https://git.eeqj.de/sneak/routewatch/issues/108). The requests run in a
+// synctest bubble, whose clock is fake, so a stall on the host does not use up
+// the stats handlers' 4-second limit.
 func TestJSONRoutesDoNotSendErrorDetails(t *testing.T) {
 	t.Parallel()

@@ -1155,8 +1191,11 @@ func TestJSONRoutesDoNotSendErrorDetails(t *testing.T) {

 	for _, tt := range tests {
 		rec := httptest.NewRecorder()
-		s.router.ServeHTTP(rec, httptest.NewRequestWithContext(
-			t.Context(), http.MethodGet, tt.path, nil))
+
+		synctest.Test(t, func(t *testing.T) {
+			s.router.ServeHTTP(rec, httptest.NewRequestWithContext(
+				t.Context(), http.MethodGet, tt.path, nil))
+		})

 		if rec.Code != tt.wantCode {
 			t.Errorf("%s: status %d, want %d; body %s",
@@ -1397,8 +1436,11 @@ func TestIPLookupKeepsRouteWhenPTRLookupDoesNotAnswer(t *testing.T) {
 	s := newServerWithTestRoutes(t)
 	s.resolver = &fakeResolver{ptrNeverAnswers: true}

-	// The request's time limit passes after the PTR lookup's.
-	ctx, cancel := context.WithTimeout(t.Context(), 2*ptrLookupTimeout)
+	// The request's time limit passes well after the PTR lookup's, so that a
+	// stall on a busy host does not use up the difference.
+	const requestTimeLimit = ptrLookupTimeout + 15*time.Second
+
+	ctx, cancel := context.WithTimeout(t.Context(), requestTimeLimit)
 	defer cancel()

 	rec := httptest.NewRecorder()
@@ -2287,9 +2329,13 @@ func settledGoroutineCount() int {
 	return prev
 }

-// waitForGoroutines waits until the goroutine count drops to target or below.
+// waitForGoroutines waits up to 15 seconds for the goroutine count to drop to
+// target or below.
 func waitForGoroutines(target int) bool {
-	for range 100 {
+	const maxWait = 15 * time.Second
+
+	deadline := time.Now().Add(maxWait)
+	for time.Now().Before(deadline) {
 		if runtime.NumGoroutine() <= target {
 			return true
 		}
@@ -76,7 +76,9 @@ func asLink(asn int) string {
 }

 // TestHomePageCardsShowTheTableFigures fills a routing table and the asns
-// table, works out the cards, and checks that each card shows its figure.
+// table, works out the cards, and checks that each card shows its figure. The
+// cards are worked out in a synctest bubble, whose clock is fake, so a stall on
+// the host does not use up the 4-second limit on their database read.
 func TestHomePageCardsShowTheTableFigures(t *testing.T) {
 	t.Parallel()

@@ -95,7 +97,9 @@ func TestHomePageCardsShowTheTableFigures(t *testing.T) {
 		t.Fatalf("GetOrCreateASNBatch: %v", err)
 	}

-	s.refreshHomeCards(t.Context())
+	synctest.Test(t, func(t *testing.T) {
+		s.refreshHomeCards(t.Context())
+	})

 	page := get(t, s, "/").Body.String()

@@ -279,7 +283,7 @@ func TestKeepHomeCardsFreshWorksThemOutEveryInterval(t *testing.T) {

 	const (
 		interval = 10 * time.Millisecond
-		maxWait  = 5 * time.Second
+		maxWait  = 15 * time.Second
 	)

 	table := emptyTable()
@@ -321,7 +325,7 @@ func TestKeepHomeCardsFreshWorksThemOutEveryInterval(t *testing.T) {
 func TestStartedServerWorksOutTheCards(t *testing.T) {
 	t.Parallel()

-	const maxWait = 5 * time.Second
+	const maxWait = 15 * time.Second

 	s := newServerWithTable(t, newCardsTable())

@@ -14,6 +14,7 @@ import (
 	"regexp"
 	"strings"
 	"testing"
+	"testing/synctest"
 	"time"

 	"git.eeqj.de/sneak/routewatch/internal/config"
@@ -163,6 +164,10 @@ func TestJSONAnswersPutNoUnitInAString(t *testing.T) {
 // router and the middleware write. Before the fix a panic in a handler, and a
 // method /status.json or the health check does not take, answered with an
 // empty body (https://git.eeqj.de/sneak/routewatch/issues/201).
+//
+// The requests run in a synctest bubble, whose clock is fake, so a stall on
+// the host does not use up the 2-second limit of the health check or the
+// 4-second limit of the stats handlers.
 func TestJSONAnswersCarryMeta(t *testing.T) {
 	t.Parallel()

@@ -181,6 +186,10 @@ func TestJSONAnswersCarryMeta(t *testing.T) {
 	s.router.Get(panicsPath, JSONValidationMiddleware(http.HandlerFunc(
 		func(http.ResponseWriter, *http.Request) { panic(errDiskIO) })).ServeHTTP)

+	failing := New(failingDB{}, newTestTable(),
+		streamer.New(logger.New(), metrics.New()), logger.New(), &config.Config{})
+	failing.resolver = &fakeResolver{}
+
 	tests := []struct {
 		method   string
 		path     string
@@ -216,42 +225,40 @@ func TestJSONAnswersCarryMeta(t *testing.T) {
 		{http.MethodGet, panicsPath, http.StatusInternalServerError},
 	}

-	for _, tt := range tests {
-		checkAnswerCarriesMeta(t, s, httptest.NewRequestWithContext(
-			t.Context(), tt.method, tt.path, nil), tt.wantCode)
-	}
+	synctest.Test(t, func(t *testing.T) {
+		for _, tt := range tests {
+			checkAnswerCarriesMeta(t, s, httptest.NewRequestWithContext(
+				t.Context(), tt.method, tt.path, nil), tt.wantCode)
+		}

-	// A request whose time limit has already passed answers 504. The handlers
-	// write the answers of the first five routes, and the JSON check on the
-	// route writes the last.
-	pastTimeLimit, cancel := context.WithDeadline(t.Context(), time.Now())
-	defer cancel()
+		// A request whose time limit has already passed answers 504. The
+		// handlers write the answers of the first five routes, and the JSON
+		// check on the route writes the last.
+		pastTimeLimit, cancel := context.WithDeadline(t.Context(), time.Now())
+		defer cancel()

-	for _, path := range []string{
-		statusJSONPath, statsPath, "/ip/" + addrInTestPrefixV4,
-		"/api/v1/ip/" + addrInTestPrefixV4, asJSONPath, writesNothingPath,
-	} {
-		checkAnswerCarriesMeta(t, s, httptest.NewRequestWithContext(
-			pastTimeLimit, http.MethodGet, path, nil), http.StatusGatewayTimeout)
-	}
+		for _, path := range []string{
+			statusJSONPath, statsPath, "/ip/" + addrInTestPrefixV4,
+			"/api/v1/ip/" + addrInTestPrefixV4, asJSONPath, writesNothingPath,
+		} {
+			checkAnswerCarriesMeta(t, s, httptest.NewRequestWithContext(
+				pastTimeLimit, http.MethodGet, path, nil), http.StatusGatewayTimeout)
+		}

-	// With a store whose reads fail, the health check answers 503, and the
-	// handlers of the other routes 500.
-	failing := New(failingDB{}, newTestTable(),
-		streamer.New(logger.New(), metrics.New()), logger.New(), &config.Config{})
-	failing.resolver = &fakeResolver{}
-
-	checkAnswerCarriesMeta(t, failing, httptest.NewRequestWithContext(
-		t.Context(), http.MethodGet, healthCheckPath, nil),
-		http.StatusServiceUnavailable)
-
-	for _, path := range []string{
-		statusJSONPath, statsPath, asJSONPath,
-		"/api/v1/ip/" + addrInTestPrefixV4, "/ip/" + addrInTestPrefixV4,
-	} {
+		// With a store whose reads fail, the health check answers 503, and
+		// the handlers of the other routes 500.
 		checkAnswerCarriesMeta(t, failing, httptest.NewRequestWithContext(
-			t.Context(), http.MethodGet, path, nil), http.StatusInternalServerError)
-	}
+			t.Context(), http.MethodGet, healthCheckPath, nil),
+			http.StatusServiceUnavailable)
+
+		for _, path := range []string{
+			statusJSONPath, statsPath, asJSONPath,
+			"/api/v1/ip/" + addrInTestPrefixV4, "/ip/" + addrInTestPrefixV4,
+		} {
+			checkAnswerCarriesMeta(t, failing, httptest.NewRequestWithContext(
+				t.Context(), http.MethodGet, path, nil), http.StatusInternalServerError)
+		}
+	})
 }

 // checkAnswerCarriesMeta serves req through the server's router, and checks
@@ -5,6 +5,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"testing"
+	"testing/synctest"
 )

 // TestRoutesAnswerHEAD sends HEAD for a page and JSON routes through the
@@ -12,15 +13,23 @@ import (
 // lookup of the caller's own address, are in the list because chi's GetHead
 // does not reach them. Before the fix every route answered HEAD with 405
 // (https://git.eeqj.de/sneak/routewatch/issues/111).
+//
+// The requests run in a synctest bubble, whose clock is fake, so a stall on
+// the host does not use up the stats handlers' 4-second limit. The resolver
+// is fake because no time limit would cut off a real DNS lookup in a bubble.
 func TestRoutesAnswerHEAD(t *testing.T) {
 	t.Parallel()

 	s := newServerWithTestRoutes(t)
+	s.resolver = &fakeResolver{}

 	for _, path := range []string{"/", statusJSONPath, statsPath, "/ip", "/ip/"} {
 		rec := httptest.NewRecorder()
-		s.router.ServeHTTP(rec, httptest.NewRequestWithContext(
-			t.Context(), http.MethodHead, path, nil))
+
+		synctest.Test(t, func(t *testing.T) {
+			s.router.ServeHTTP(rec, httptest.NewRequestWithContext(
+				t.Context(), http.MethodHead, path, nil))
+		})

 		if rec.Code != http.StatusOK {
 			t.Errorf("HEAD %s: status %d, want %d; body %s",
@@ -22,10 +22,10 @@ func TestStopClosesTheConnectionOfARequestStillRunning(t *testing.T) {
 		stopDeadline = 100 * time.Millisecond
 		// waitTimeout is how long the test waits for the request to reach
 		// the handler, and then for the client to see its connection closed.
-		waitTimeout = 2 * time.Second
+		waitTimeout = 15 * time.Second
 		// readHeaderTimeout bounds the test server's read of the request
 		// header, as every http.Server must.
-		readHeaderTimeout = time.Second
+		readHeaderTimeout = waitTimeout
 	)

 	release := make(chan struct{})
@@ -14,6 +14,7 @@ import (
 	"strings"
 	"sync/atomic"
 	"testing"
+	"testing/synctest"
 	"time"

 	"git.eeqj.de/sneak/routewatch/internal/logger"
@@ -398,7 +399,7 @@ func TestStopQueuesTheHeldStateMessages(t *testing.T) {
 	const (
 		held    = 2
 		lines   = held + 1
-		maxWait = 5 * time.Second
+		maxWait = 15 * time.Second
 	)

 	srv := httptest.NewServer(http.HandlerFunc(
@@ -478,15 +479,15 @@ func TestStopQueuesTheHeldStateMessages(t *testing.T) {
 // TestStopReturnsByItsDeadline stops a streamer whose handler has a full queue
 // and a STATE message held for it, and a worker that stays busy until the test
 // ends, as one does whose handler waits for a database write. Stop must return
-// within its deadline plus a small margin instead of waiting for room on the
-// queue and for the worker, and log as not handed over the held message and
-// every message on the queue.
+// within its deadline plus a margin instead of waiting for room on the queue
+// and for the worker, and log as not handed over the held message and every
+// message on the queue.
 func TestStopReturnsByItsDeadline(t *testing.T) {
 	t.Parallel()

 	const (
 		deadline = 100 * time.Millisecond
-		margin   = 2 * time.Second
+		margin   = 15 * time.Second
 	)

 	var logs bytes.Buffer
@@ -610,10 +611,34 @@ func TestReconnectWhenServerNeverAnswers(t *testing.T) {
 	checkReconnect(t, neverAnswer, idleTimeout)
 }

-// TestStreamNotDroppedWhileLinesArrive has the server send lines well within
-// the idle timeout for several times the timeout, then end the response. Each
-// line must start the idle timeout over, so the stream lasts until the server
-// ends it instead of being dropped as idle.
+// pipeTransport answers every request with a response whose body write fills.
+// The body fails when the request's context ends, as a connection's does.
+// write gets that context, so that it can end when the request does.
+type pipeTransport struct {
+	write func(context.Context, io.Writer)
+}
+
+func (p pipeTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	body, w := io.Pipe()
+
+	context.AfterFunc(req.Context(), func() {
+		_ = w.CloseWithError(req.Context().Err())
+	})
+
+	go func(ctx context.Context) {
+		p.write(ctx, w)
+
+		_ = w.Close()
+	}(req.Context())
+
+	return &http.Response{StatusCode: http.StatusOK, Body: body}, nil
+}
+
+// TestStreamNotDroppedWhileLinesArrive has a response send lines well within
+// the idle timeout for several times the timeout, then end. Each line must
+// start the idle timeout over, so the stream lasts until the response ends
+// instead of being dropped as idle. It runs in a synctest bubble, whose clock
+// is fake, so a stall on the host does not use up the timeout.
 func TestStreamNotDroppedWhileLinesArrive(t *testing.T) {
 	t.Parallel()

@@ -623,26 +648,35 @@ func TestStreamNotDroppedWhileLinesArrive(t *testing.T) {
 		sendFor      = 5 * idleTimeout
 	)

-	srv := httptest.NewServer(http.HandlerFunc(
-		func(w http.ResponseWriter, _ *http.Request) {
+	// The streamer is made outside the bubble. Its metrics start a goroutine
+	// that never returns, and a bubble waits for each of its goroutines to
+	// return.
+	s := New(logger.New(), metrics.New())
+	s.idleTimeout = idleTimeout
+	s.client = &http.Client{Transport: pipeTransport{
+		write: func(ctx context.Context, w io.Writer) {
 			deadline := time.Now().Add(sendFor)
 			for time.Now().Before(deadline) {
 				_, _ = io.WriteString(w, updateLine)

-				flush(w)
-				time.Sleep(lineInterval)
+				// The wait ends with the stream. A bubble's clock stops when
+				// the test function returns, and a goroutine then still
+				// asleep panics the test binary.
+				select {
+				case <-ctx.Done():
+					return
+				case <-time.After(lineInterval):
+				}
 			}
-		}))
-	defer srv.Close()
+		},
+	}}

-	s := New(logger.New(), metrics.New())
-	s.url = srv.URL
-	s.idleTimeout = idleTimeout
-
-	err := s.stream(context.Background())
-	if !errors.Is(err, errStreamEnded) {
-		t.Fatalf("stream returned %v, want %v", err, errStreamEnded)
-	}
+	synctest.Test(t, func(t *testing.T) {
+		err := s.stream(context.Background())
+		if !errors.Is(err, errStreamEnded) {
+			t.Fatalf("stream returned %v, want %v", err, errStreamEnded)
+		}
+	})
 }

 // TestStreamReadsLongLine has the server send one UPDATE line of about
@@ -706,7 +740,7 @@ func TestHandlerStatsReadWhileMessagesAreDropped(t *testing.T) {
 	const (
 		lines       = 5
 		wantDropped = lines - 2
-		maxWait     = 5 * time.Second
+		maxWait     = 15 * time.Second
 	)

 	srv := httptest.NewServer(http.HandlerFunc(
@@ -825,7 +859,7 @@ func checkReconnect(
 ) {
 	t.Helper()

-	const maxWait = 5 * time.Second
+	const maxWait = 15 * time.Second

 	tracker := metrics.New()
 	connectedAtReconnect := make(chan bool, 1)
@@ -896,9 +930,13 @@ func settledGoroutineCount() int {
 	return prev
 }

-// waitForGoroutines waits until the goroutine count drops to target or below.
+// waitForGoroutines waits up to 15 seconds for the goroutine count to drop to
+// target or below.
 func waitForGoroutines(target int) bool {
-	for range 100 {
+	const maxWait = 15 * time.Second
+
+	deadline := time.Now().Add(maxWait)
+	for time.Now().Before(deadline) {
 		if runtime.NumGoroutine() <= target {
 			return true
 		}