examples: make examples testable

examples/m2mrecur/example_test.go

@@ -0,0 +1,92 @@
+// Copyright 2019-present Facebook Inc. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+
+	"github.com/facebookincubator/ent/examples/m2mrecur/ent/user"
+
+	"github.com/facebookincubator/ent/examples/m2mrecur/ent"
+
+	_ "github.com/mattn/go-sqlite3"
+)
+
+func Example_M2MRecur() {
+	client, err := ent.Open("sqlite3", "file:ent?mode=memory&cache=shared&_fk=1")
+	if err != nil {
+		log.Fatalf("failed opening connection to sqlite: %v", err)
+	}
+	defer client.Close()
+	ctx := context.Background()
+	// Run the auto migration tool.
+	if err := client.Schema.Create(ctx); err != nil {
+		log.Fatalf("failed creating schema resources: %v", err)
+	}
+	if err := Do(ctx, client); err != nil {
+		log.Fatal(err)
+	}
+	// Output:
+	// [User(id=2, age=28, name=nati)]
+	// []
+	// []
+	// [User(id=1, age=30, name=a8m)]
+	// [28]
+	// [a8m]
+}
+
+func Do(ctx context.Context, client *ent.Client) error {
+	// Unlike `Save`, `SaveX` panics if an error occurs.
+	a8m := client.User.
+		Create().
+		SetAge(30).
+		SetName("a8m").
+		SaveX(ctx)
+	nati := client.User.
+		Create().
+		SetAge(28).
+		SetName("nati").
+		AddFollowers(a8m).
+		SaveX(ctx)
+
+	// Query following/followers:
+
+	flw := a8m.QueryFollowing().AllX(ctx)
+	fmt.Println(flw)
+	// Output: [User(id=2, age=28, name=nati)]
+
+	flr := a8m.QueryFollowers().AllX(ctx)
+	fmt.Println(flr)
+	// Output: []
+
+	flw = nati.QueryFollowing().AllX(ctx)
+	fmt.Println(flw)
+	// Output: []
+
+	flr = nati.QueryFollowers().AllX(ctx)
+	fmt.Println(flr)
+	// Output: [User(id=1, age=30, name=a8m)]
+
+	// Traverse the graph:
+
+	ages := nati.
+		QueryFollowers().       // [a8m]
+		QueryFollowing().       // [nati]
+		GroupBy(user.FieldAge). // [28]
+		IntsX(ctx)
+	fmt.Println(ages)
+	// Output: [28]
+
+	names := client.User.
+		Query().
+		Where(user.Not(user.HasFollowers())).
+		GroupBy(user.FieldName).
+		StringsX(ctx)
+	fmt.Println(names)
+	// Output: [a8m]
+	return nil
+}