Keep each test database when the pool replaces its connection (closes #209)

SQLite deletes a shared in-memory database when its last connection
closes. A query cancelled while it runs makes the pool close its
connection, so a test could lose all its tables and rows at random.

The new package internal/dbtest has NewTestDatabaseURL. It returns the
URL of a new in-memory database with a random name and holds one
connection to it open until the test ends. The db, handlers,
ircserver, server and service tests take their database URL from it.
The test-support lint rule keeps the package out of the server binary.

A new test cancels a query on such a database, checks with a TEMP
table that the connection was replaced, and checks that a row is
still there.

Model: opus-5-5

.golangci.yml

@@ -61,6 +61,10 @@ linters:
               desc: >-
                 Test-support code belongs in test files and in packages whose
                 directory name ends in test, not in the shipped binary.
+            - pkg: sneak.berlin/go/neoirc/internal/dbtest
+              desc: >-
+                Test-support code belongs in test files and in packages whose
+                directory name ends in test, not in the shipped binary.
     # Only decisions already recorded in the Go package defaults are
     # listed here. Every entry matches the module path exactly.
     gomodguard_v2:

internal/db/db_test.go

@@ -12,6 +12,7 @@ import (
 	"go.uber.org/fx/fxtest"
 	"sneak.berlin/go/neoirc/internal/config"
 	"sneak.berlin/go/neoirc/internal/db"
+	"sneak.berlin/go/neoirc/internal/dbtest"
 	"sneak.berlin/go/neoirc/internal/globals"
 	"sneak.berlin/go/neoirc/internal/logger"
 )
@@ -163,7 +164,7 @@ func TestForeignKeysOnAfterCancelledQuery(t *testing.T) {
 func TestNewTestDatabaseURLKeepsDataAfterCancelledQuery(t *testing.T) {
 	t.Parallel()
 
-	database, err := startDatabase(t, db.NewTestDatabaseURL(t))
+	database, err := startDatabase(t, dbtest.NewTestDatabaseURL(t))
 	if err != nil {
 		t.Fatal(err)
 	}

internal/db/export_test.go

@@ -6,13 +6,15 @@ import (
 	"fmt"
 	"log/slog"
 	"testing"
+
+	"sneak.berlin/go/neoirc/internal/dbtest"
 )
 
 // NewTestDatabase creates an in-memory database for testing.
 func NewTestDatabase(tb testing.TB) (*Database, error) {
 	tb.Helper()
 
-	dsn := NewTestDatabaseURL(tb) + "&_pragma=foreign_keys(1)"
+	dsn := dbtest.NewTestDatabaseURL(tb) + "&_pragma=foreign_keys(1)"
 
 	conn, err := sql.Open("sqlite", dsn)
 	if err != nil {

internal/db/testing.go

@@ -2,40 +2,10 @@ package db
 
 import (
 	"context"
-	"crypto/rand"
 	"database/sql"
 	"log/slog"
-	"testing"
 )
 
-// NewTestDatabaseURL returns the URL of a new, empty in-memory
-// database for one test. SQLite deletes an in-memory database when
-// its last connection closes. A pool closes a connection when a query
-// on it is cancelled while it runs. So this function holds a
-// connection of its own open until the test ends.
-func NewTestDatabaseURL(tb testing.TB) string {
-	tb.Helper()
-
-	// A random name, so that no other test can share the database.
-	dbURL := "file:" + rand.Text() + "?mode=memory&cache=shared"
-
-	pool, err := sql.Open("sqlite", dbURL)
-	if err != nil {
-		tb.Fatalf("open test database: %v", err)
-	}
-
-	tb.Cleanup(func() { _ = pool.Close() })
-
-	conn, err := pool.Conn(tb.Context())
-	if err != nil {
-		tb.Fatalf("connect to test database: %v", err)
-	}
-
-	tb.Cleanup(func() { _ = conn.Close() })
-
-	return dbURL
-}
-
 // NewTestDatabaseFromConn creates a Database wrapping an
 // existing *sql.DB connection.  Intended for integration
 // tests in other packages.

internal/dbtest/dbtest.go

@@ -0,0 +1,39 @@
+// Package dbtest gives each test a database of its own. Only tests
+// may import it.
+package dbtest
+
+import (
+	"crypto/rand"
+	"database/sql"
+	"testing"
+
+	_ "modernc.org/sqlite" // registers the sqlite driver
+)
+
+// NewTestDatabaseURL returns the URL of a new, empty in-memory
+// database for one test. SQLite deletes an in-memory database when
+// its last connection closes. A pool closes a connection when a query
+// on it is cancelled while it runs. So this function holds a
+// connection of its own open until the test ends.
+func NewTestDatabaseURL(tb testing.TB) string {
+	tb.Helper()
+
+	// A random name, so that no other test can share the database.
+	dbURL := "file:" + rand.Text() + "?mode=memory&cache=shared"
+
+	pool, err := sql.Open("sqlite", dbURL)
+	if err != nil {
+		tb.Fatalf("open test database: %v", err)
+	}
+
+	tb.Cleanup(func() { _ = pool.Close() })
+
+	conn, err := pool.Conn(tb.Context())
+	if err != nil {
+		tb.Fatalf("connect to test database: %v", err)
+	}
+
+	tb.Cleanup(func() { _ = conn.Close() })
+
+	return dbURL
+}

internal/handlers/api_test.go

@@ -27,6 +27,7 @@ import (
 	api "sneak.berlin/go/neoirc/internal/cli/api"
 	"sneak.berlin/go/neoirc/internal/config"
 	"sneak.berlin/go/neoirc/internal/db"
+	"sneak.berlin/go/neoirc/internal/dbtest"
 	"sneak.berlin/go/neoirc/internal/globals"
 	"sneak.berlin/go/neoirc/internal/handlers"
 	"sneak.berlin/go/neoirc/internal/hashcash"
@@ -163,7 +164,7 @@ func newTestServerWith(
 	viperMu.Lock()
 	defer viperMu.Unlock()
 
-	dbURL := db.NewTestDatabaseURL(t)
+	dbURL := dbtest.NewTestDatabaseURL(t)
 	copyTemplateDB(t, dbURL)
 
 	var (

internal/ircserver/server_test.go

@@ -19,6 +19,7 @@ import (
 	"sneak.berlin/go/neoirc/internal/broker"
 	"sneak.berlin/go/neoirc/internal/config"
 	"sneak.berlin/go/neoirc/internal/db"
+	"sneak.berlin/go/neoirc/internal/dbtest"
 	"sneak.berlin/go/neoirc/internal/globals"
 	"sneak.berlin/go/neoirc/internal/ircserver"
 	"sneak.berlin/go/neoirc/internal/logger"
@@ -106,7 +107,7 @@ func newTestEnvWithResolver(
 ) *testEnv {
 	t.Helper()
 
-	conn, err := sql.Open("sqlite", db.NewTestDatabaseURL(t))
+	conn, err := sql.Open("sqlite", dbtest.NewTestDatabaseURL(t))
 	if err != nil {
 		t.Fatalf("open db: %v", err)
 	}

internal/server/server_test.go

@@ -18,6 +18,7 @@ import (
 	"sneak.berlin/go/neoirc/internal/broker"
 	"sneak.berlin/go/neoirc/internal/config"
 	"sneak.berlin/go/neoirc/internal/db"
+	"sneak.berlin/go/neoirc/internal/dbtest"
 	"sneak.berlin/go/neoirc/internal/globals"
 	"sneak.berlin/go/neoirc/internal/handlers"
 	"sneak.berlin/go/neoirc/internal/healthcheck"
@@ -240,7 +241,7 @@ func newApp(
 			stats.New,
 		),
 		fx.Decorate(func(cfg *config.Config) *config.Config {
-			cfg.DBURL = db.NewTestDatabaseURL(t)
+			cfg.DBURL = dbtest.NewTestDatabaseURL(t)
 			cfg.Port = port
 
 			return cfg

internal/service/service_test.go

@@ -22,6 +22,7 @@ import (
 	"sneak.berlin/go/neoirc/internal/broker"
 	"sneak.berlin/go/neoirc/internal/config"
 	"sneak.berlin/go/neoirc/internal/db"
+	"sneak.berlin/go/neoirc/internal/dbtest"
 	"sneak.berlin/go/neoirc/internal/globals"
 	"sneak.berlin/go/neoirc/internal/hashcash"
 	"sneak.berlin/go/neoirc/internal/logger"
@@ -45,7 +46,7 @@ type testEnv struct {
 func newTestEnv(t *testing.T) *testEnv {
 	t.Helper()
 
-	dbURL := db.NewTestDatabaseURL(t)
+	dbURL := dbtest.NewTestDatabaseURL(t)
 
 	var (
 		database *db.Database