test: start migrating dbauthz tests to mocked db (#19257)

This PR adds a framework to move to a mocked db. And therefore massively speed up these tests.

testutil/faker.go

@@ -0,0 +1,67 @@
+package testutil
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/brianvoe/gofakeit/v7"
+	"github.com/stretchr/testify/require"
+)
+
+// Fake will populate any zero fields in the provided struct with fake data.
+// Non-zero fields will remain unchanged.
+// Usage:
+//
+//	key := Fake(t, faker, database.APIKey{
+//	  TokenName: "keep-my-name",
+//	})
+func Fake[T any](t *testing.T, faker *gofakeit.Faker, seed T) T {
+	t.Helper()
+
+	var tmp T
+	err := faker.Struct(&tmp)
+	require.NoError(t, err, "failed to generate fake data for type %T", tmp)
+
+	mergeZero(&seed, tmp)
+	return seed
+}
+
+// mergeZero merges the fields of src into dst, but only if the field in dst is
+// currently the zero value.
+// Make sure `dst` is a pointer to a struct, otherwise the fields are not assignable.
+func mergeZero(dst any, src any) {
+	srcv := reflect.ValueOf(src)
+	if srcv.Kind() == reflect.Ptr {
+		srcv = srcv.Elem()
+	}
+	remain := [][2]reflect.Value{
+		{reflect.ValueOf(dst).Elem(), srcv},
+	}
+
+	// Traverse the struct fields and set them only if they are currently zero.
+	// This is a breadth-first traversal of the struct fields. Struct definitions
+	// Should not be that deep, so we should not hit any stack overflow issues.
+	for {
+		if len(remain) == 0 {
+			return
+		}
+		dv, sv := remain[0][0], remain[0][1]
+		remain = remain[1:] //
+		for i := 0; i < dv.NumField(); i++ {
+			df := dv.Field(i)
+			sf := sv.Field(i)
+			if !df.CanSet() {
+				continue
+			}
+			if df.IsZero() { // only write if currently zero
+				df.Set(sf)
+				continue
+			}
+
+			if dv.Field(i).Kind() == reflect.Struct {
+				// If the field is a struct, we need to traverse it as well.
+				remain = append(remain, [2]reflect.Value{df, sf})
+			}
+		}
+	}
+}

testutil/faker_test.go

@@ -0,0 +1,71 @@
+package testutil_test
+
+import (
+	"testing"
+
+	"github.com/brianvoe/gofakeit/v7"
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/require"
+
+	"github.com/coder/coder/v2/coderd/database"
+	"github.com/coder/coder/v2/testutil"
+)
+
+type simpleStruct struct {
+	ID          uuid.UUID
+	Name        string
+	Description string
+	Age         int `fake:"{number:18,60}"`
+}
+
+type nestedStruct struct {
+	Person  simpleStruct
+	Address string
+}
+
+func TestFake(t *testing.T) {
+	t.Parallel()
+
+	t.Run("Simple", func(t *testing.T) {
+		t.Parallel()
+
+		faker := gofakeit.New(0)
+		person := testutil.Fake(t, faker, simpleStruct{
+			Name: "alice",
+		})
+		require.Equal(t, "alice", person.Name)
+		require.NotEqual(t, uuid.Nil, person.ID)
+		require.NotEmpty(t, person.Description)
+		require.Greater(t, person.Age, 17, "Age should be greater than 17")
+		require.Less(t, person.Age, 61, "Age should be less than 61")
+	})
+
+	t.Run("Nested", func(t *testing.T) {
+		t.Parallel()
+
+		faker := gofakeit.New(0)
+		person := testutil.Fake(t, faker, nestedStruct{
+			Person: simpleStruct{
+				Name: "alice",
+			},
+		})
+		require.Equal(t, "alice", person.Person.Name)
+		require.NotEqual(t, uuid.Nil, person.Person.ID)
+		require.NotEmpty(t, person.Person.Description)
+		require.Greater(t, person.Person.Age, 17, "Age should be greater than 17")
+		require.NotEmpty(t, person.Address)
+	})
+
+	t.Run("DatabaseType", func(t *testing.T) {
+		t.Parallel()
+
+		faker := gofakeit.New(0)
+		id := uuid.New()
+		key := testutil.Fake(t, faker, database.APIKey{
+			UserID:    id,
+			TokenName: "keep-my-name",
+		})
+		require.Equal(t, id, key.UserID)
+		require.NotEmpty(t, key.TokenName)
+	})
+}