database/sql: fix close rows error ignored in Next

Change-Id: I19f0d764e2a6122307f3f26a6dd3be7b1155c73b
GitHub-Last-Rev: 9f1f883c45
GitHub-Pull-Request: golang/go#52756
Reviewed-on: https://go-review.googlesource.com/c/go/+/404794
Reviewed-by: Daniel Theophanes <kardianos@gmail.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Daniel Theophanes <kardianos@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/database/sql/fakedb_test.go

@@ -1089,6 +1089,9 @@ type rowsCursor struct {
 	// This is separate from the fakeConn.line to allow for drivers that
 	// can start multiple queries on the same transaction at the same time.
 	line int64
+
+	// closeErr is returned when rowsCursor.Close
+	closeErr error
 }
 
 func (rc *rowsCursor) touchMem() {
@@ -1100,7 +1103,7 @@ func (rc *rowsCursor) Close() error {
 	rc.touchMem()
 	rc.parentMem.touchMem()
 	rc.closed = true
-	return nil
+	return rc.closeErr
 }
 
 func (rc *rowsCursor) Columns() []string {

src/database/sql/sql.go

@@ -3331,6 +3331,8 @@ func (rs *Rows) close(err error) error {
 		rs.closeStmt.Close()
 	}
 	rs.releaseConn(err)
+
+	rs.lasterr = rs.lasterrOrErrLocked(err)
 	return err
 }
 

src/database/sql/sql_test.go

@@ -2636,6 +2636,39 @@ func TestRowsImplicitClose(t *testing.T) {
 	}
 }
 
+func TestRowsCloseError(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer db.Close()
+	rows, err := db.Query("SELECT|people|age,name|")
+	if err != nil {
+		t.Fatalf("Query: %v", err)
+	}
+	type row struct {
+		age  int
+		name string
+	}
+	got := []row{}
+
+	rc, ok := rows.rowsi.(*rowsCursor)
+	if !ok {
+		t.Fatal("not using *rowsCursor")
+	}
+	rc.closeErr = errors.New("rowsCursor: failed to close")
+
+	for rows.Next() {
+		var r row
+		err = rows.Scan(&r.age, &r.name)
+		if err != nil {
+			t.Fatalf("Scan: %v", err)
+		}
+		got = append(got, r)
+	}
+	err = rows.Err()
+	if err != rc.closeErr {
+		t.Fatalf("unexpected err: got %v, want %v", err, rc.closeErr)
+	}
+}
+
 func TestStmtCloseOrder(t *testing.T) {
 	db := newTestDB(t, "people")
 	defer closeDB(t, db)