refactoring of ExternalServiceCredentialGenerator

service/src/test/java/org/whispersystems/textsecuregcm/util/MockHelper.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2023 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.whispersystems.textsecuregcm.util;
+
+import org.mockito.Mockito;
+
+public final class MockHelper {
+
+  private MockHelper() {
+    // utility class
+  }
+
+  @FunctionalInterface
+  public interface MockInitializer<T> {
+
+    void init(T mock) throws Exception;
+  }
+
+  public static <T> T buildMock(final Class<T> clazz, final MockInitializer<T> initializer) throws RuntimeException {
+    final T mock = Mockito.mock(clazz);
+    try {
+      initializer.init(mock);
+    } catch (Exception e) {
+      throw new RuntimeException(e);
+    }
+    return mock;
+  }
+}