Add identify-user support

collect_app/src/androidTest/java/org/odk/collect/android/espressoutils/pages/Page.java

@@ -192,7 +192,7 @@ private static ViewAction rotateToLandscape() {
 
     public T waitForRotationToEnd() {
         try {
-            Thread.sleep(2000);
+            Thread.sleep(3000);
         } catch (InterruptedException e) {
             Timber.i(e);
         }

collect_app/src/androidTest/java/org/odk/collect/android/formentry/audit/IdentifyUserTest.java

@@ -64,7 +64,7 @@ public void openingForm_andEnteringBlankIdentity_remainsOnIdentityPrompt() {
         new MainMenuPage(rule)
                 .clickFillBlankForm()
                 .clickOnFormWithIdentityPrompt("Identify User")
-                .enterIdentity("")
+                .enterIdentity("  ")
                 .clickKeyboardEnterWithValidationError();
     }
 

collect_app/src/main/java/org/odk/collect/android/formentry/audit/IdentityPromptViewModel.java

@@ -5,6 +5,8 @@
 import androidx.lifecycle.MutableLiveData;
 import androidx.lifecycle.ViewModel;
 
+import static org.odk.collect.android.utilities.StringUtils.isBlank;
+
 public class IdentityPromptViewModel extends ViewModel {
 
     private final MutableLiveData<Boolean> formEntryCancelled = new MutableLiveData<>(false);
@@ -43,9 +45,11 @@ public void promptClosing() {
 
     private void updateRequiresIdentity() {
         this.requiresIdentity.setValue(
-                auditEventLogger != null &&
-                        auditEventLogger.isUserRequired() &&
-                        (auditEventLogger.getUser() == null || auditEventLogger.getUser().isEmpty())
+                auditEventLogger != null && auditEventLogger.isUserRequired() && !userIsValid(auditEventLogger.getUser())
         );
     }
+
+    private static boolean userIsValid(String user) {
+        return user != null && !user.isEmpty() && !isBlank(user);
+    }
 }

collect_app/src/main/java/org/odk/collect/android/utilities/StringUtils.java

@@ -0,0 +1,21 @@
+package org.odk.collect.android.utilities;
+
+import static java.lang.Character.isWhitespace;
+
+public class StringUtils {
+
+    private StringUtils() {
+    }
+
+    public static boolean isBlank(String string) {
+        char[] chars = string.toCharArray();
+
+        for (char character : chars) {
+            if (!isWhitespace(character)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+}

collect_app/src/test/java/org/odk/collect/android/utilities/StringUtilsTest.java

@@ -0,0 +1,20 @@
+package org.odk.collect.android.utilities;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.odk.collect.android.utilities.StringUtils.isBlank;
+
+public class StringUtilsTest {
+
+    @Test
+    public void whenStringIsJustWhitespace_returnsTrue() {
+        assertTrue(isBlank(" "));
+    }
+
+    @Test
+    public void whenStringContainsWhitespace_returnsFalse() {
+        assertFalse(isBlank(" hello "));
+    }
+}