From a20cb4ca5c14ff27bdf16989d450c83b22f156d8 Mon Sep 17 00:00:00 2001 From: Tim Möhlmann Date: Thu, 13 Aug 2020 11:56:31 +0300 Subject: database/sql: make Rows.Scan properly wrap underlying errors The prior implementation used the format verb %v which unfortunately improperly wrapped any underlying scanner errors, and we couldn't use errors.Is nor errors.As. This change fixes that by using the %w verb. Added a unit to ensure that both error sub string matching works, but also that errors.Is works as expected. Fixes #38099 Change-Id: Iea667041dd8081d961246f77f2542330417292dc Reviewed-on: https://go-review.googlesource.com/c/go/+/248337 Reviewed-by: Emmanuel Odeke Reviewed-by: Daniel Theophanes Run-TryBot: Emmanuel Odeke TryBot-Result: Gobot Gobot --- src/database/sql/sql_test.go | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) (limited to 'src/database/sql/sql_test.go') diff --git a/src/database/sql/sql_test.go b/src/database/sql/sql_test.go index 5727f0d8aa..762d42f54b 100644 --- a/src/database/sql/sql_test.go +++ b/src/database/sql/sql_test.go @@ -4149,6 +4149,41 @@ func TestQueryExecContextOnly(t *testing.T) { } } +type alwaysErrScanner struct{} + +var errTestScanWrap = errors.New("errTestScanWrap") + +func (alwaysErrScanner) Scan(interface{}) error { + return errTestScanWrap +} + +// Issue 38099: Ensure that Rows.Scan properly wraps underlying errors. +func TestRowsScanProperlyWrapsErrors(t *testing.T) { + db := newTestDB(t, "people") + defer closeDB(t, db) + + rows, err := db.Query("SELECT|people|age|") + if err != nil { + t.Fatalf("Query: %v", err) + } + + var res alwaysErrScanner + + for rows.Next() { + err = rows.Scan(&res) + if err == nil { + t.Fatal("expecting back an error") + } + if !errors.Is(err, errTestScanWrap) { + t.Fatalf("errors.Is mismatch\n%v\nWant: %v", err, errTestScanWrap) + } + // Ensure that error substring matching still correctly works. + if !strings.Contains(err.Error(), errTestScanWrap.Error()) { + t.Fatalf("Error %v does not contain %v", err, errTestScanWrap) + } + } +} + // badConn implements a bad driver.Conn, for TestBadDriver. // The Exec method panics. type badConn struct{} -- cgit v1.3