Ensure assignment date is in ISO8601 format (FF-1933) (#46)

eppo/build.gradle

@@ -4,7 +4,7 @@ plugins {
 }
 
 group = "cloud.eppo"
-version = "1.0.7"
+version = "1.0.8"
 
 android {
     compileSdk 33

eppo/src/main/java/cloud/eppo/android/EppoClient.java

@@ -39,7 +39,8 @@ public class EppoClient {
     // Useful for testing in situations where we want to mock the http client
     private static EppoHttpClient httpClientOverride = null;
 
-    private EppoClient(Application application, String apiKey, String host, AssignmentLogger assignmentLogger, boolean isGracefulMode) {
+    private EppoClient(Application application, String apiKey, String host, AssignmentLogger assignmentLogger,
+            boolean isGracefulMode) {
         EppoHttpClient httpClient = httpClientOverride == null ? new EppoHttpClient(host, apiKey) : httpClientOverride;
         ConfigurationStore configStore = new ConfigurationStore(application);
         requestor = new ConfigurationRequestor(configStore, httpClient);
@@ -133,7 +134,7 @@ protected EppoValue getTypedAssignment(String subjectKey, String flagKey, Subjec
         String allocationKey = rule.getAllocationKey();
         Allocation allocation = flag.getAllocations().get(allocationKey);
         if (allocation == null) {
-            Log.w(TAG, "unexpected unknown allocation key \""+allocationKey+"\"");
+            Log.w(TAG, "unexpected unknown allocation key \"" + allocationKey + "\"");
             return null;
         }
 
@@ -157,9 +158,14 @@ protected EppoValue getTypedAssignment(String subjectKey, String flagKey, Subjec
                 variationToLog = typedValue.stringValue();
             }
 
-            Assignment assignment = new Assignment(experimentKey,
-                    flagKey, allocationKey, variationToLog,
-                    subjectKey, Utils.getISODate(new Date()), subjectAttributes);
+            Assignment assignment = Assignment.createWithCurrentDate(
+                experimentKey,
+                flagKey, 
+                allocationKey, 
+                variationToLog,
+                subjectKey, 
+                subjectAttributes
+            );
             assignmentLogger.logAssignment(assignment);
         }
 

eppo/src/main/java/cloud/eppo/android/logging/Assignment.java

@@ -1,6 +1,9 @@
 package cloud.eppo.android.logging;
 
 import cloud.eppo.android.dto.SubjectAttributes;
+import cloud.eppo.android.util.Utils;
+
+import java.util.Date;
 
 public class Assignment {
     private String experiment;
@@ -18,8 +21,7 @@ public Assignment(
             String variation,
             String subject,
             String timestamp,
-            SubjectAttributes subjectAttributes
-    ) {
+            SubjectAttributes subjectAttributes) {
         this.experiment = experiment;
         this.featureFlag = featureFlag;
         this.allocation = allocation;
@@ -29,6 +31,17 @@ public Assignment(
         this.subjectAttributes = subjectAttributes;
     }
 
+    public static Assignment createWithCurrentDate(
+            String experiment,
+            String featureFlag,
+            String allocation,
+            String variation,
+            String subject,
+            SubjectAttributes subjectAttributes) {
+        return new Assignment(experiment, featureFlag, allocation, variation, subject,
+                Utils.getISODate(new Date()), subjectAttributes);
+    }
+
     public String getExperiment() {
         return experiment;
     }

eppo/src/main/java/cloud/eppo/android/util/Utils.java

@@ -6,10 +6,9 @@
 import java.math.BigInteger;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
-import java.text.DateFormat;
 import java.text.SimpleDateFormat;
 import java.util.Date;
-import java.util.TimeZone;
+import java.util.Locale;
 
 import cloud.eppo.android.dto.ShardRange;
 
@@ -50,10 +49,9 @@ public static void validateNotEmptyOrNull(String input, String errorMessage) {
     }
 
     public static String getISODate(Date date) {
-        TimeZone tz = TimeZone.getTimeZone("UTC");
-        DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
-        df.setTimeZone(tz);
-        return df.format(date);
+        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.US);
+        dateFormat.setTimeZone(java.util.TimeZone.getTimeZone("UTC"));
+        return dateFormat.format(date);
     }
 
     public static SharedPreferences getSharedPrefs(Context context) {

eppo/src/test/java/cloud/eppo/android/UtilsTest.java

@@ -0,0 +1,62 @@
+package cloud.eppo.android;
+
+import org.junit.Test;
+import static org.junit.Assert.*;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import java.util.Locale;
+import java.util.TimeZone;
+
+import cloud.eppo.android.util.Utils;
+
+public class UtilsTest {
+
+    @Test
+    public void testGetISODate() {
+        String isoDate = Utils.getISODate(new Date());
+        assertNotNull("ISO date should not be null", isoDate);
+
+        // Verify the format
+        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.US);
+        dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
+        try {
+            Date date = dateFormat.parse(isoDate);
+            assertNotNull("Parsed date should not be null", date);
+
+            // Optionally, verify the date is not too far from the current time
+            long currentTime = System.currentTimeMillis();
+            long parsedTime = date.getTime();
+            assertTrue("The parsed date should be within a reasonable range of the current time",
+                    Math.abs(currentTime - parsedTime) < 10000); // for example, within 10 seconds
+        } catch (ParseException e) {
+            fail("Parsing the ISO date failed: " + e.getMessage());
+        }
+    }
+
+    @Test
+    public void testGetCurrentDateISOInDifferentLocale() {
+        // Arrange
+        Locale defaultLocale = Locale.getDefault();
+        try {
+            // Set locale to Arabic
+            Locale.setDefault(new Locale("ar"));
+            String isoDate = Utils.getISODate(new Date());
+
+            // Act
+            // Check if the date is in the correct ISO 8601 format
+            // This is a simple regex check to see if the string follows the
+            // YYYY-MM-DDTHH:MM:SSZ pattern
+            boolean isISO8601 = isoDate.matches("\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}Z");
+
+            // Assert
+            assertTrue("Date should be in ISO 8601 format", isISO8601);
+
+        } catch (Exception e) {
+            fail("Test failed with exception: " + e.getMessage());
+        } finally {
+            // Reset locale back to original
+            Locale.setDefault(defaultLocale);
+        }
+    }
+}