Clean up some stuff around ImportExportTest.

core-util-jvm/build.gradle.kts

@@ -17,6 +17,8 @@ java {
 }
 
 dependencies {
+  implementation(libs.kotlin.reflect)
+
   testImplementation(testLibs.junit.junit)
   testImplementation(testLibs.assertj.core)
 }

core-util-jvm/src/main/java/org/signal/core/util/test/TestUtils.kt

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2024 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.signal.core.util.test
+
+import kotlin.reflect.full.memberProperties
+import kotlin.reflect.jvm.isAccessible
+
+/**
+ * Returns a string containing the differences between the expected and actual objects.
+ * Useful for diffing complex data classes in your tests.
+ */
+inline fun <reified T : Any> getObjectDiff(expected: T, actual: T): String {
+  val builder = StringBuilder()
+
+  val properties = T::class.memberProperties
+
+  for (prop in properties) {
+    prop.isAccessible = true
+    val expectedValue = prop.get(expected)
+    val actualValue = prop.get(actual)
+    if (expectedValue != actualValue) {
+      builder.append("[${prop.name}] Expected: $expectedValue, Actual: $actualValue\n")
+    }
+  }
+
+  return builder.toString()
+}