adding test around matrix user id check

matrix-sdk-android/src/test/java/org/matrix/android/sdk/api/MatrixPatternsTest.kt

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2022 The Matrix.org Foundation C.I.C.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+package org.matrix.android.sdk.api
+
+import org.amshove.kluent.shouldBeEqualTo
+import org.junit.Test
+
+class MatrixPatternsTest {
+
+    @Test
+    fun `given user id cases, when checking isUserId, then returns expected`() {
+            val cases = listOf(
+                    UserIdCase("foobar", isUserId = false),
+                    UserIdCase("@foobar", isUserId = false),
+                    UserIdCase("foobar@matrix.org", isUserId = false),
+                    UserIdCase("@foobar: matrix.org", isUserId = false),
+                    UserIdCase("@foobar:matrix.org", isUserId = true),
+            )
+
+            cases.forEach { (input, expected) ->
+                MatrixPatterns.isUserId(input) shouldBeEqualTo expected
+            }
+    }
+
+}
+
+private data class UserIdCase(val input: String, val isUserId: Boolean)