prevent full feed fetching next time we fetch it if caching header values changed but content did not (#1037)

commafeed-server/src/test/java/com/commafeed/backend/feed/FeedFetcherTest.java

@@ -0,0 +1,60 @@
+package com.commafeed.backend.feed;
+
+import java.io.IOException;
+import java.util.Date;
+import java.util.Set;
+
+import org.apache.commons.codec.digest.DigestUtils;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.Mockito;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import com.commafeed.backend.HttpGetter;
+import com.commafeed.backend.HttpGetter.HttpResult;
+import com.commafeed.backend.HttpGetter.NotModifiedException;
+import com.commafeed.backend.urlprovider.FeedURLProvider;
+import com.rometools.rome.io.FeedException;
+
+@ExtendWith(MockitoExtension.class)
+class FeedFetcherTest {
+
+	@Mock
+	private FeedParser parser;
+
+	@Mock
+	private HttpGetter getter;
+
+	@Mock
+	private Set<FeedURLProvider> urlProviders;
+
+	private FeedFetcher fetcher;
+
+	@BeforeEach
+	void init() {
+		fetcher = new FeedFetcher(parser, getter, urlProviders);
+	}
+
+	@Test
+	void updatesHeaderWhenContentDitNotChange() throws FeedException, IOException, NotModifiedException {
+		String url = "https://aaa.com";
+		String lastModified = "last-modified-1";
+		String etag = "etag-1";
+		byte[] content = "content".getBytes();
+		String lastContentHash = DigestUtils.sha1Hex(content);
+
+		Mockito.when(getter.getBinary(url, lastModified, etag, 20000))
+				.thenReturn(new HttpResult(content, "content-type", "last-modified-2", "etag-2", 20, null));
+
+		NotModifiedException e = Assertions.assertThrows(NotModifiedException.class,
+				() -> fetcher.fetch(url, false, lastModified, etag, new Date(), lastContentHash));
+
+		Assertions.assertEquals("last-modified-2", e.getNewLastModifiedHeader());
+		Assertions.assertEquals("etag-2", e.getNewEtagHeader());
+
+	}
+
+}