create new error module, which displays errors before migration

scm-webapp/src/test/java/sonia/scm/boot/SingleViewTest.java

@@ -0,0 +1,99 @@
+package sonia.scm.boot;
+
+import com.google.inject.Injector;
+import com.google.inject.servlet.GuiceFilter;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Captor;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import javax.servlet.FilterConfig;
+import javax.servlet.ServletContext;
+import javax.servlet.ServletContextEvent;
+import javax.servlet.ServletContextListener;
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletRequest;
+import java.io.IOException;
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.*;
+
+@ExtendWith(MockitoExtension.class)
+class SingleViewTest {
+
+  @Mock
+  private ServletContext servletContext;
+
+  @Mock
+  private HttpServletRequest request;
+
+  @Captor
+  private ArgumentCaptor<Injector> captor;
+
+  private GuiceFilter guiceFilter;
+
+  @BeforeEach
+  void setUpGuiceFilter() throws ServletException {
+    guiceFilter = new GuiceFilter();
+    FilterConfig config = mock(FilterConfig.class);
+    doReturn(servletContext).when(config).getServletContext();
+    guiceFilter.init(config);
+  }
+
+  @AfterEach
+  void tearDownGuiceFilter() {
+    guiceFilter.destroy();
+  }
+
+  @Test
+  void shouldCreateViewControllerForError() {
+    ServletContextListener listener = SingleView.error(new IOException("awesome io"));
+    when(request.getContextPath()).thenReturn("/scm");
+
+    ViewController instance = findViewController(listener);
+    assertErrorViewController(instance, "awesome io");
+  }
+
+  @Test
+  void shouldBindServlets() {
+    ServletContextListener listener = SingleView.error(new IOException("awesome io"));
+    Injector injector = findInjector(listener);
+
+    assertThat(injector.getInstance(StaticResourceServlet.class)).isNotNull();
+    assertThat(injector.getInstance(SingleViewServlet.class)).isNotNull();
+  }
+
+  @SuppressWarnings("unchecked")
+  private void assertErrorViewController(ViewController instance, String contains) {
+    assertThat(instance.getTemplate()).isEqualTo("/templates/error.mustache");
+
+    View view = instance.createView(request);
+    assertThat(view.getStatusCode()).isEqualTo(500);
+    assertThat(view.getModel()).isInstanceOfSatisfying(Map.class, map -> {
+        assertThat(map).containsEntry("contextPath", "/scm");
+        String error = (String) map.get("error");
+        assertThat(error).contains(contains);
+      }
+    );
+  }
+
+  private ViewController findViewController(ServletContextListener listener) {
+    Injector injector = findInjector(listener);
+    return injector.getInstance(ViewController.class);
+  }
+
+  private Injector findInjector(ServletContextListener listener) {
+    listener.contextInitialized(new ServletContextEvent(servletContext));
+
+    verify(servletContext).setAttribute(anyString(), captor.capture());
+
+    return captor.getValue();
+  }
+
+
+}