Fix early filter invalid symbols during register

src/main/kotlin/io/github/wulkanowy/api/repository/RegisterRepository.kt

@@ -76,7 +76,7 @@ class RegisterRepository(
                 Single.just(Jsoup.parse(cert.wresult.replace(":", ""), "", Parser.xmlParser())
                     .select("[AttributeName$=\"Instance\"] samlAttributeValue")
                     .map { it.text().trim() }
-                    .filter { it.matches("[a-zA-Z]*".toRegex()) } // early filter invalid symbols
+                    .filter { it.matches("[a-z0-9]*".toRegex()) } // early filter invalid symbols
                     .ifEmpty { listOf("opole", "gdansk", "tarnow", "rzeszow") } // fallback
                     .map { Pair(it, cert) }
                 )

src/test/kotlin/io/github/wulkanowy/api/repository/RegisterRepositoryTest.kt

@@ -15,6 +15,7 @@ import io.github.wulkanowy.api.service.StudentService
 import io.reactivex.observers.TestObserver
 import okhttp3.mockwebserver.MockResponse
 import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
 import org.junit.Test
 import java.net.CookieManager
 
@@ -144,11 +145,14 @@ class RegisterRepositoryTest : BaseLocalTest() {
 
         server.start(3000)
 
-        val res = getRegisterRepository(" glubczyce2").getStudents()
+        val res = getRegisterRepository("Default").getStudents()
         val observer = TestObserver<List<Student>>()
         res.subscribe(observer)
         observer.assertTerminated()
 
-        assertEquals("/glubczyce2/Account/LogOn", server.takeRequest().path)
+        assertEquals("/Default/Account/LogOn", server.takeRequest().path)
+        assertTrue(server.takeRequest().path.startsWith("/Account/LogOn?ReturnUrl=%2FDefault"))
+        assertEquals("/default/LoginEndpoint.aspx", server.takeRequest().path)
+        assertEquals("/glubczyce2/LoginEndpoint.aspx", server.takeRequest().path)
     }
 }