🧪 [testing improvement] Add tests for TusServletRequest trailer header fallback (#129)

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Co-authored-by: tomdesair <14034630+tomdesair@users.noreply.github.com>

Author: tomdesair

src/test/java/me/desair/tus/server/util/TusServletRequestTest.java

@@ -0,0 +1,121 @@
+package me.desair.tus.server.util;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import static org.mockito.Mockito.when;
+
+import jakarta.servlet.ReadListener;
+import jakarta.servlet.ServletInputStream;
+import jakarta.servlet.http.HttpServletRequest;
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+import org.apache.commons.io.IOUtils;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+
+@RunWith(MockitoJUnitRunner.class)
+public class TusServletRequestTest {
+
+  @Mock private HttpServletRequest servletRequest;
+
+  private TusServletRequest tusServletRequest;
+
+  @Before
+  public void setUp() {
+    tusServletRequest = new TusServletRequest(servletRequest, true);
+  }
+
+  @Test
+  public void getHeaderFromSuper() {
+    when(servletRequest.getHeader("X-My-Header")).thenReturn("my-value");
+
+    assertEquals("my-value", tusServletRequest.getHeader("X-My-Header"));
+  }
+
+  @Test
+  public void getHeaderFromTrailer() throws Exception {
+    when(servletRequest.getHeader("Transfer-Encoding")).thenReturn("chunked");
+    when(servletRequest.getHeader("X-My-Trailer")).thenReturn(null);
+
+    String chunkedContent = "5\r\n" + "hello\r\n" + "0\r\n" + "X-My-Trailer: trailer-value\r\n\r\n";
+    InputStream bais = new ByteArrayInputStream(chunkedContent.getBytes(StandardCharsets.UTF_8));
+
+    when(servletRequest.getInputStream())
+        .thenReturn(
+            new ServletInputStream() {
+              @Override
+              public boolean isFinished() {
+                return false;
+              }
+
+              @Override
+              public boolean isReady() {
+                return true;
+              }
+
+              @Override
+              public void setReadListener(ReadListener readListener) {}
+
+              @Override
+              public int read() throws IOException {
+                return bais.read();
+              }
+            });
+
+    // Read the whole input stream to parse trailers
+    InputStream contentInputStream = tusServletRequest.getContentInputStream();
+    IOUtils.toByteArray(contentInputStream);
+
+    // Verify trailer header is returned
+    assertEquals("trailer-value", tusServletRequest.getHeader("X-My-Trailer"));
+  }
+
+  @Test
+  public void getHeaderBlankFallsBackToTrailer() throws Exception {
+    when(servletRequest.getHeader("Transfer-Encoding")).thenReturn("chunked");
+    when(servletRequest.getHeader("X-My-Trailer")).thenReturn("");
+
+    String chunkedContent = "5\r\n" + "hello\r\n" + "0\r\n" + "X-My-Trailer: trailer-value\r\n\r\n";
+    InputStream bais = new ByteArrayInputStream(chunkedContent.getBytes(StandardCharsets.UTF_8));
+
+    when(servletRequest.getInputStream())
+        .thenReturn(
+            new ServletInputStream() {
+              @Override
+              public boolean isFinished() {
+                return false;
+              }
+
+              @Override
+              public boolean isReady() {
+                return true;
+              }
+
+              @Override
+              public void setReadListener(ReadListener readListener) {}
+
+              @Override
+              public int read() throws IOException {
+                return bais.read();
+              }
+            });
+
+    // Read the whole input stream to parse trailers
+    InputStream contentInputStream = tusServletRequest.getContentInputStream();
+    IOUtils.toByteArray(contentInputStream);
+
+    // Verify trailer header is returned because super returned a blank string
+    assertEquals("trailer-value", tusServletRequest.getHeader("X-My-Trailer"));
+  }
+
+  @Test
+  public void getHeaderNotFound() {
+    when(servletRequest.getHeader("X-My-Header")).thenReturn(null);
+    assertNull(tusServletRequest.getHeader("X-My-Header"));
+  }
+}