Make runnable examples drop the databases they create

example_helpers_test.go

@@ -0,0 +1,34 @@
+package testdb_test
+
+import (
+	"context"
+	"fmt"
+	"testing"
+)
+
+// exampleT stands in for the *testing.T a runnable example does not have;
+// see postgres/example_helpers_test.go for the full story. The examples
+// here close their databases by hand, but a real stand-in keeps them honest
+// about what they call on t.
+type exampleT struct {
+	testing.TB
+	cleanups []func()
+}
+
+func newExampleT() *exampleT { return &exampleT{} }
+
+func (t *exampleT) Helper()                  {}
+func (t *exampleT) Cleanup(f func())         { t.cleanups = append(t.cleanups, f) }
+func (t *exampleT) Context() context.Context { return context.Background() }
+func (t *exampleT) Failed() bool             { return false }
+func (t *exampleT) Logf(string, ...any)      {}
+
+func (t *exampleT) Errorf(format string, args ...any) { fmt.Printf("error: "+format+"\n", args...) }
+func (t *exampleT) Fatalf(format string, args ...any) { panic(fmt.Sprintf(format, args...)) }
+func (t *exampleT) Fatal(args ...any)                 { panic(fmt.Sprint(args...)) }
+
+func (t *exampleT) done() {
+	for i := len(t.cleanups) - 1; i >= 0; i-- {
+		t.cleanups[i]()
+	}
+}

example_test.go

@@ -3,7 +3,6 @@ package testdb_test
 import (
 	"context"
 	"fmt"
-	"testing"
 
 	"github.com/bashhack/testdb"
 	"github.com/bashhack/testdb/postgres"
@@ -12,7 +11,8 @@ import (
 // Example_new demonstrates using testdb.New with a custom initializer
 // for full control over database initialization.
 func Example_new() {
-	t := &testing.T{}
+	t := newExampleT()
+	defer t.done()
 
 	provider := &postgres.PostgresProvider{}
 	initializer := &postgres.PoolInitializer{}
@@ -48,7 +48,8 @@ func Example_new() {
 // Example_dsnOnly demonstrates using testdb to get just a DSN
 // without automatic connection initialization.
 func Example_dsnOnly() {
-	t := &testing.T{}
+	t := newExampleT()
+	defer t.done()
 
 	provider := &postgres.PostgresProvider{}
 
@@ -78,7 +79,8 @@ func Example_dsnOnly() {
 // Example_customInitializer shows implementing a custom initializer
 // for integration with ORMs or custom database types.
 func Example_customInitializer() {
-	t := &testing.T{}
+	t := newExampleT()
+	defer t.done()
 
 	provider := &postgres.PostgresProvider{}
 	initializer := &exampleInitializer{}