add coverage for global, route-specific, ordering and short-circuit

Author: Ericthilen

src/test/java/org/example/ConfigurableFilterPipelineTest.java

@@ -0,0 +1,101 @@
+package org.example.server;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class ConfigurableFilterPipelineTest {
+
+    @Test
+    void global_filter_runs() {
+
+        List<String> events = new ArrayList<>();
+
+        HttpFilter filter = new TestFilter(events, false);
+
+        List<FilterRegistration> regs = List.of(
+                new FilterRegistration(filter, 1, null)
+        );
+
+        ConfigurableFilterPipeline pipeline =
+                new ConfigurableFilterPipeline(regs);
+
+        pipeline.execute(
+                new HttpRequest("GET", "/home"),
+                new TestHandler(events)
+        );
+
+        assertEquals(
+                List.of("filter", "handler"),
+                events
+        );
+    }
+
+    @Test
+    void filter_can_stop_chain() {
+
+        List<String> events = new ArrayList<>();
+
+        HttpFilter stopFilter = new TestFilter(events, true);
+
+        List<FilterRegistration> regs = List.of(
+                new FilterRegistration(stopFilter, 1, null)
+        );
+
+        ConfigurableFilterPipeline pipeline =
+                new ConfigurableFilterPipeline(regs);
+
+        HttpResponse response = pipeline.execute(
+                new HttpRequest("GET", "/home"),
+                new TestHandler(events)
+        );
+
+        assertEquals(403, response.getStatusCode());
+        assertEquals(List.of("filter"), events);
+    }
+
+    // =====================
+    // Test helper classes
+    // =====================
+
+    static class TestFilter implements HttpFilter {
+
+        private final List<String> events;
+        private final boolean stop;
+
+        TestFilter(List<String> events, boolean stop) {
+            this.events = events;
+            this.stop = stop;
+        }
+
+        @Override
+        public HttpResponse handle(HttpRequest request, FilterChain chain) {
+
+            events.add("filter");
+
+            if (stop) {
+                return new HttpResponse(403, "Stopped");
+            }
+
+            return chain.next(request);
+        }
+    }
+
+    static class TestHandler implements TerminalHandler {
+
+        private final List<String> events;
+
+        TestHandler(List<String> events) {
+            this.events = events;
+        }
+
+        @Override
+        public HttpResponse handle(HttpRequest request) {
+            events.add("handler");
+            return new HttpResponse(200, "OK");
+        }
+    }
+}