code review 7399046: database/sql: clarify that DB.Prepare's stmt is safe fo...

src/pkg/database/sql/sql_test.go

 // Copyright 2011 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 package sql
 
 import (
         "database/sql/driver"
         "fmt"
         "reflect"
@@ skipping 255 matching lines @@
         } {
                 if err := stmt.QueryRow(tt.name).Scan(&age); err != nil {
                         t.Errorf("%d: on %q, QueryRow/Scan: %v", n, tt.name, err)
                 } else if age != tt.want {
                         t.Errorf("%d: age=%d, want %d", n, age, tt.want)
                 }
         }
 
 }
 
+// golang.org/issue/3734
+func TestStatementQueryRowConcurrent(t *testing.T) {
+        db := newTestDB(t, "people")
+        defer closeDB(t, db)
+        stmt, err := db.Prepare("SELECT|people|age|name=?")
+        if err != nil {
+                t.Fatalf("Prepare: %v", err)
+        }
+        defer stmt.Close()
+
+        const n = 10
+        ch := make(chan error, n)
+        for i := 0; i < n; i++ {
+                go func() {
+                        var age int
+                        err := stmt.QueryRow("Alice").Scan(&age)
+                        if err == nil && age != 1 {
+                                err = fmt.Errorf("unexpected age %d", age)
+                        }
+                        ch <- err
+                }()
+        }
+        for i := 0; i < n; i++ {
+                if err := <-ch; err != nil {
+                        t.Error(err)
+                }
+        }
+}
+
 // just a test of fakedb itself
 func TestBogusPreboundParameters(t *testing.T) {
         db := newTestDB(t, "foo")
         defer closeDB(t, db)
         exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")
         _, err := db.Prepare("INSERT|t1|name=?,age=bogusconversion")
         if err == nil {
                 t.Fatalf("expected error")
         }
         if err.Error() != `fakedb: invalid conversion to int32 from "bogusconversion"` {
@@ skipping 374 matching lines @@
                 id := i + 1
                 if err := db.QueryRow("SELECT|t|nullf|id=?", id).Scan(bindVal); err != nil {
                         t.Errorf("id=%d Scan: %v", id, err)
                 }
                 bindValDeref := reflect.ValueOf(bindVal).Elem().Interface()
                 if !reflect.DeepEqual(bindValDeref, spec.rows[i].scanNullVal) {
                         t.Errorf("id=%d got %#v, want %#v", id, bindValDeref, spec.rows[i].scanNullVal)
                 }
         }
 }