Use java.time classes for stored verification code expiration; add tests.

service/src/main/java/org/whispersystems/textsecuregcm/auth/StoredVerificationCode.java

@@ -8,12 +8,14 @@ package org.whispersystems.textsecuregcm.auth;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 
+import com.google.common.annotations.VisibleForTesting;
 import org.whispersystems.textsecuregcm.util.Util;
 
 import javax.annotation.Nullable;
 import java.security.MessageDigest;
+import java.time.Duration;
+import java.time.Instant;
 import java.util.Optional;
-import java.util.concurrent.TimeUnit;
 
 public class StoredVerificationCode {
 
@@ -30,6 +32,8 @@ public class StoredVerificationCode {
   @Nullable
   private final String twilioVerificationSid;
 
+  public static final Duration EXPIRATION = Duration.ofMinutes(10);
+
   @JsonCreator
   public StoredVerificationCode(
       @JsonProperty("code") final String code,
@@ -60,7 +64,12 @@ public class StoredVerificationCode {
   }
 
   public boolean isValid(String theirCodeString) {
-    if (timestamp + TimeUnit.MINUTES.toMillis(10) < System.currentTimeMillis()) {
+    return isValid(theirCodeString, Instant.now());
+  }
+
+  @VisibleForTesting
+  boolean isValid(String theirCodeString, Instant currentTime) {
+    if (Instant.ofEpochMilli(timestamp).plus(EXPIRATION).isBefore(currentTime)) {
       return false;
     }
 

service/src/test/java/org/whispersystems/textsecuregcm/auth/StoredVerificationCodeTest.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2013-2021 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.whispersystems.textsecuregcm.auth;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.util.stream.Stream;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class StoredVerificationCodeTest {
+
+  @ParameterizedTest
+  @MethodSource
+  void isValid(final StoredVerificationCode storedVerificationCode, final String code, final Instant currentTime, final boolean expectValid) {
+    assertEquals(expectValid, storedVerificationCode.isValid(code, currentTime));
+  }
+
+  private static Stream<Arguments> isValid() {
+    final Instant now = Instant.now();
+
+    return Stream.of(
+        Arguments.of(new StoredVerificationCode("code", now.toEpochMilli(), null, null), "code", now, true),
+        Arguments.of(new StoredVerificationCode("code", now.toEpochMilli(), null, null), "incorrect", now, false),
+        Arguments.of(new StoredVerificationCode("code", now.toEpochMilli(), null, null), "code", now.plus(Duration.ofHours(1)), false),
+        Arguments.of(new StoredVerificationCode("", now.toEpochMilli(), null, null), "", now, false)
+    );
+  }
+}