Prevent leading and trailing whitespace in group names.

app/src/test/java/org/thoughtcrime/securesms/util/StringUtilTest_whitespace_handling.java

@@ -0,0 +1,54 @@
+package org.thoughtcrime.securesms.util;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
+import java.util.Arrays;
+import java.util.Collection;
+
+import static org.junit.Assert.assertEquals;
+
+@RunWith(Parameterized.class)
+public final class StringUtilTest_whitespace_handling {
+
+  private final String  input;
+  private final String  expectedTrimmed;
+  private final boolean isVisuallyEmpty;
+
+  @Parameterized.Parameters
+  public static Collection<Object[]> data() {
+    return Arrays.asList(new Object[][]{
+
+      { "", "", true },
+      { " ", "", true },
+      { "A", "A", false },
+      { " B", "B", false },
+      { "C ", "C", false },
+
+      /* Unicode whitespace */
+      { "\u200E", "", true },
+      { "\u200F", "", true },
+      { "\u2007", "", true },
+      { "\u2007\u200FA\tB\u200EC\u200E\u200F", "A\tB\u200EC", false },
+
+    });
+  }
+
+  public StringUtilTest_whitespace_handling(String input, String expectedTrimmed, boolean isVisuallyEmpty) {
+    this.input           = input;
+    this.expectedTrimmed = expectedTrimmed;
+    this.isVisuallyEmpty = isVisuallyEmpty;
+  }
+
+  @Test
+  public void isVisuallyEmpty() {
+    assertEquals(isVisuallyEmpty, StringUtil.isVisuallyEmpty(input));
+  }
+
+  @Test
+  public void trim() {
+    assertEquals(expectedTrimmed, StringUtil.trimToVisualBounds(input));
+  }
+
+}