Fixing bug where expiration dates were improperly rendered in the CLI

cli/src/main/java/keywhiz/cli/Printing.java

@@ -17,10 +17,12 @@
 
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Strings;
 import com.google.common.base.Throwables;
 import java.io.IOException;
 import java.text.DateFormat;
+import java.time.Instant;
 import java.util.Comparator;
 import java.util.Date;
 import java.util.List;
@@ -289,13 +291,14 @@ public void printSecretWithDetails(long secretID) {
     }
   }
 
-  private String apiDateToString(ApiDate apiDate) {
-    return epochSecondToString(apiDate.toEpochSecond() * 1000);
+  @VisibleForTesting
+  static String apiDateToString(ApiDate apiDate) {
+    return epochSecondToString(apiDate.toEpochSecond());
   }
 
-  private String epochSecondToString(long epochSecond) {
-    Date d = new Date(epochSecond);
-    return DateFormat.getDateTimeInstance().format(d);
+  @VisibleForTesting
+  static String epochSecondToString(long epochSecond) {
+    return Instant.ofEpochSecond(epochSecond).toString();
   }
 
   public void printAllClients(List<Client> clients) {

cli/src/test/java/keywhiz/cli/PrintingTest.java

@@ -0,0 +1,20 @@
+package keywhiz.cli;
+
+import keywhiz.api.ApiDate;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class PrintingTest {
+  @Test
+  public void apiDateToString() {
+    String iso8601 = "2024-03-03T00:00:00Z";
+    ApiDate apiDate = ApiDate.parse(iso8601);
+    assertEquals(iso8601, Printing.apiDateToString(apiDate));
+  }
+
+  @Test
+  public void epochSecondToString() {
+    assertEquals("2024-03-03T00:00:00Z", Printing.epochSecondToString(1709424000L));
+  }
+}