Test the db_url derived from a state_dir starting with //

The test sets state_dir to a temporary directory with a / put in front,
opens the derived db_url with the SQLite driver, and checks that the
database is state.sqlite3 in that directory, in WAL mode. It fails while
the URL starts file://, where SQLite reads the first directory name as
a host. The open-and-check part of the test before it moves into a
helper both tests call.

Model: opus-5-5

internal/config/config_validation_internal_test.go

@@ -158,9 +158,39 @@ func TestDerivedDBURLOpensStateDirHoldingURLCharacters(t *testing.T) {
 
 	t.Logf("state_dir %q gives db_url %q", stateDir, c.DBURL)
 
-	db, err := sql.Open("sqlite", c.DBURL)
+	checkDBURLOpensFileInWALMode(t, c.DBURL, filepath.Join(stateDir, "state.sqlite3"))
+}
+
+// TestDerivedDBURLOpensStateDirStartingWithTwoSlashes opens the db_url
+// derived from a state_dir that starts with //, and checks that the
+// database is state.sqlite3 in that directory, in WAL mode. Written right
+// after file:, such a name gives a URL starting file://, and SQLite reads
+// the first directory name as a host and refuses to open it.
+func TestDerivedDBURLOpensStateDirStartingWithTwoSlashes(t *testing.T) {
+	t.Parallel()
+
+	dir := t.TempDir()
+	stateDir := "/" + dir
+
+	c, err := configFromYAML(t, signingKeyLine+"state_dir: "+stateDir+"\n")
 	if err != nil {
-		t.Fatalf("failed to open %q: %v", c.DBURL, err)
+		t.Fatalf("config with state_dir %q should be valid, got: %v", stateDir, err)
+	}
+
+	t.Logf("state_dir %q gives db_url %q", stateDir, c.DBURL)
+
+	checkDBURLOpensFileInWALMode(t, c.DBURL, filepath.Join(dir, "state.sqlite3"))
+}
+
+// checkDBURLOpensFileInWALMode opens dbURL with the SQLite driver pixad
+// uses, and checks that the database is in WAL mode and is the file
+// dbFile.
+func checkDBURLOpensFileInWALMode(t *testing.T, dbURL, dbFile string) {
+	t.Helper()
+
+	db, err := sql.Open("sqlite", dbURL)
+	if err != nil {
+		t.Fatalf("failed to open %q: %v", dbURL, err)
 	}
 
 	t.Cleanup(func() { _ = db.Close() })
@@ -169,18 +199,16 @@ func TestDerivedDBURLOpensStateDirHoldingURLCharacters(t *testing.T) {
 
 	err = db.QueryRowContext(t.Context(), "PRAGMA journal_mode").Scan(&journalMode)
 	if err != nil {
-		t.Fatalf("failed to read the journal mode of %q: %v", c.DBURL, err)
+		t.Fatalf("failed to read the journal mode of %q: %v", dbURL, err)
 	}
 
 	if journalMode != "wal" {
-		t.Errorf("journal mode of %q = %q, want wal", c.DBURL, journalMode)
+		t.Errorf("journal mode of %q = %q, want wal", dbURL, journalMode)
 	}
 
-	dbFile := filepath.Join(stateDir, "state.sqlite3")
-
 	_, err = os.Stat(dbFile)
 	if err != nil {
-		t.Errorf("opening %q did not create %q: %v", c.DBURL, dbFile, err)
+		t.Errorf("opening %q did not create %q: %v", dbURL, dbFile, err)
 	}
 }