avoid t.Fatal() in tests (#9189)

I've been burned a few times by tests that simply fatal, requiring me to
run another build to learn more about what the mismatch was. Avoid this.

This is part of a long running goal of mine to make testing "better".

model/oauth_test.go

@@ -6,6 +6,8 @@ package model
 import (
 	"strings"
 	"testing"
+
+	"github.com/stretchr/testify/require"
 )
 
 func TestOAuthAppJson(t *testing.T) {
@@ -52,52 +54,32 @@ func TestOAuthAppPreUpdate(t *testing.T) {
 func TestOAuthAppIsValid(t *testing.T) {
 	app := OAuthApp{}
 
-	if err := app.IsValid(); err == nil {
-		t.Fatal()
-	}
+	require.NotNil(t, app.IsValid())
 
 	app.Id = NewId()
-	if err := app.IsValid(); err == nil {
-		t.Fatal()
-	}
+	require.NotNil(t, app.IsValid())
 
 	app.CreateAt = 1
-	if err := app.IsValid(); err == nil {
-		t.Fatal()
-	}
+	require.NotNil(t, app.IsValid())
 
 	app.UpdateAt = 1
-	if err := app.IsValid(); err == nil {
-		t.Fatal()
-	}
+	require.NotNil(t, app.IsValid())
 
 	app.CreatorId = NewId()
-	if err := app.IsValid(); err == nil {
-		t.Fatal()
-	}
+	require.NotNil(t, app.IsValid())
 
 	app.ClientSecret = NewId()
-	if err := app.IsValid(); err == nil {
-		t.Fatal()
-	}
+	require.NotNil(t, app.IsValid())
 
 	app.Name = "TestOAuthApp"
-	if err := app.IsValid(); err == nil {
-		t.Fatal()
-	}
+	require.NotNil(t, app.IsValid())
 
 	app.CallbackUrls = []string{"https://nowhere.com"}
-	if err := app.IsValid(); err == nil {
-		t.Fatal()
-	}
+	require.NotNil(t, app.IsValid())
 
 	app.Homepage = "https://nowhere.com"
-	if err := app.IsValid(); err != nil {
-		t.Fatal()
-	}
+	require.Nil(t, app.IsValid())
 
 	app.IconURL = "https://nowhere.com/icon_image.png"
-	if err := app.IsValid(); err != nil {
-		t.Fatal()
-	}
+	require.Nil(t, app.IsValid())
 }