extauth: refactor enterprise auth tests (#879)

oauthex/client_test.go

@@ -0,0 +1,88 @@
+// Copyright 2026 The Go MCP SDK Authors. All rights reserved.
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+package oauthex
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+)
+
+func TestClientCredentials_Validate(t *testing.T) {
+	tests := []struct {
+		name    string
+		creds   ClientCredentials
+		wantErr string
+	}{
+		{
+			name:  "valid public client",
+			creds: ClientCredentials{ClientID: "my-client"},
+		},
+		{
+			name: "valid confidential client",
+			creds: ClientCredentials{
+				ClientID: "my-client",
+				ClientSecretAuth: &ClientSecretAuth{
+					ClientSecret: "my-secret",
+				},
+			},
+		},
+		{
+			name:    "empty client ID",
+			creds:   ClientCredentials{},
+			wantErr: "ClientID is required",
+		},
+		{
+			name: "empty secret in ClientSecretAuth",
+			creds: ClientCredentials{
+				ClientID:         "my-client",
+				ClientSecretAuth: &ClientSecretAuth{},
+			},
+			wantErr: "ClientSecret is required",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := tt.creds.Validate()
+			if tt.wantErr == "" {
+				if err != nil {
+					t.Fatalf("Validate() unexpected error: %v", err)
+				}
+				return
+			}
+			if err == nil {
+				t.Fatalf("Validate() expected error containing %q, got nil", tt.wantErr)
+			}
+			if !strings.Contains(err.Error(), tt.wantErr) {
+				t.Fatalf("Validate() error = %v, want error containing %q", err, tt.wantErr)
+			}
+		})
+	}
+}
+
+// TestClientCredentials_ValidateCoversAllAuthFields uses reflection to detect
+// when new authentication method fields are added to ClientCredentials without
+// updating Validate. If this test fails, update Validate() to handle the new
+// field and increment knownAuthMethods.
+func TestClientCredentials_ValidateCoversAllAuthFields(t *testing.T) {
+	const knownAuthMethods = 1 // ClientSecretAuth
+
+	typ := reflect.TypeOf(ClientCredentials{})
+	var pointerFields int
+	for i := range typ.NumField() {
+		f := typ.Field(i)
+		if f.Name == "ClientID" {
+			continue
+		}
+		if f.Type.Kind() != reflect.Ptr {
+			t.Errorf("field %q is %v, expected a pointer to an auth method struct", f.Name, f.Type.Kind())
+		}
+		pointerFields++
+	}
+
+	if pointerFields != knownAuthMethods {
+		t.Fatalf("ClientCredentials has %d auth method fields but Validate only knows about %d -- update Validate() and this test", pointerFields, knownAuthMethods)
+	}
+}