Handle zero or more spaces after commas when parsing Accept-Encoding

nima/http/encoding/encoding/pom.xml

@@ -46,6 +46,16 @@
             <scope>provided</scope>
             <optional>true</optional>
         </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.hamcrest</groupId>
+            <artifactId>hamcrest-all</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>

nima/http/encoding/encoding/src/main/java/io/helidon/nima/http/encoding/ContentEncodingSupportImpl.java

@@ -95,12 +95,7 @@ public ContentEncoder encoder(Headers headers) {
             Accept-Encoding: gzip, compress, br
             Accept-Encoding: br;q=1.0, gzip;q=0.8, *;q=0.1
          */
-        String[] values = acceptEncoding.split(", ");
-        List<EncodingWithQ> supported = new ArrayList<>(values.length);
-        for (String value : values) {
-            supported.add(EncodingWithQ.parse(value));
-        }
-        Collections.sort(supported);
+        List<EncodingWithQ> supported = encodings(acceptEncoding);
         for (EncodingWithQ encodingWithQ : supported) {
             if ("*".equals(encodingWithQ.encoding)) {
                 return firstEncoder;
@@ -113,7 +108,23 @@ public ContentEncoder encoder(Headers headers) {
         return ContentEncoder.NO_OP;
     }
 
-    private static class EncodingWithQ implements Comparable<EncodingWithQ> {
+    /**
+     * Extract encodings from header value and sort them based on quality.
+     *
+     * @param acceptEncoding comma-separated list of encodings
+     * @return sorted list of encodings
+     */
+    static List<EncodingWithQ> encodings(String acceptEncoding) {
+        String[] values = acceptEncoding.split(",");
+        List<EncodingWithQ> supported = new ArrayList<>(values.length);
+        for (String value : values) {
+            supported.add(EncodingWithQ.parse(value));
+        }
+        Collections.sort(supported);
+        return supported;
+    }
+
+    static class EncodingWithQ implements Comparable<EncodingWithQ> {
         private final String encoding;
         private final double q;
 
@@ -125,7 +136,7 @@ private static class EncodingWithQ implements Comparable<EncodingWithQ> {
         static EncodingWithQ parse(String value) {
             if (value.indexOf(';') != -1) {
                 int index = value.indexOf(';');
-                String encoding = value.substring(0, index);
+                String encoding = value.substring(0, index).trim();
                 String qString = value.substring(index + 1); // q=0.1
                 index = qString.indexOf('=');
                 if (index == -1) {

nima/http/encoding/encoding/src/test/java/io/helidon/nima/http/encoding/ContentEncodingSupportTest.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2023 Oracle and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.helidon.nima.http.encoding;
+
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+import io.helidon.nima.http.encoding.ContentEncodingSupportImpl.EncodingWithQ;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static io.helidon.nima.http.encoding.ContentEncodingSupportImpl.encodings;
+
+class ContentEncodingSupportTest {
+
+    @Test
+    void testEncodingsParserOne() {
+        List<EncodingWithQ> encodings = encodings("gzip");
+        assertThat(encodings.size(), is(1));
+        assertThat(encodings.get(0).toString(), is("gzip;q=1.0"));
+    }
+
+    @Test
+    void testEncodingsParserMany() {
+        List<EncodingWithQ> encodings = encodings("gzip,compress,  br  ");
+        assertThat(encodings.size(), is(3));
+        assertThat(encodings.get(0).toString(), is("gzip;q=1.0"));
+        assertThat(encodings.get(1).toString(), is("compress;q=1.0"));
+        assertThat(encodings.get(2).toString(), is("br;q=1.0"));
+    }
+
+    @Test
+    void testEncodingsParserWithQs() {
+        List<EncodingWithQ> encodings = encodings("gzip;q=1.0, deflate;q=0.6,  identity;q=0.3");
+        assertThat(encodings.size(), is(3));
+        assertThat(encodings.get(0).toString(), is("gzip;q=1.0"));
+        assertThat(encodings.get(1).toString(), is("deflate;q=0.6"));
+        assertThat(encodings.get(2).toString(), is("identity;q=0.3"));
+    }
+}