Removes trailing slash from the URL just when just present

core/src/main/java/feign/RequestTemplate.java

@@ -89,6 +89,18 @@ public final class RequestTemplate implements Serializable {
     }
   }
 
+  private static boolean isHttpUrl(CharSequence value) {
+    return value.length() >= 4 && value.subSequence(0, 3).equals("http".substring(0,  3));
+  }
+
+  private static CharSequence removeTrailingSlash(CharSequence charSequence) {
+    if (charSequence != null && charSequence.length() > 0 && charSequence.charAt(charSequence.length() - 1) == '/') {
+      return charSequence.subSequence(0, charSequence.length() - 1);
+    } else {
+      return charSequence;
+    }
+  }
+
   /**
    * Expands a {@code template}, such as {@code username}, using the {@code variables} supplied. Any
    * unresolved parameters will remain. <br> Note that if you'd like curly braces literally in the
@@ -249,6 +261,12 @@ public final class RequestTemplate implements Serializable {
 
   /* @see #url() */
   public RequestTemplate insert(int pos, CharSequence value) {
+    if(isHttpUrl(value)) {
+      value = removeTrailingSlash(value);
+      if(url.length() > 0 && url.charAt(0) != '/') {
+        url.insert(0, '/');
+      }
+    }
     url.insert(pos, pullAnyQueriesOutOfUrl(new StringBuilder(value)));
     return this;
   }

core/src/test/java/feign/FeignBuilderTest.java

@@ -54,6 +54,50 @@ public class FeignBuilderTest {
         .hasBody("request data");
   }
 
+  @Test
+  public void testUrlPathConcatUrlTrailingSlash() throws Exception {
+    server.enqueue(new MockResponse().setBody("response data"));
+
+    String url = "http://localhost:" + server.getPort() + "/";
+    TestInterface api = Feign.builder().target(TestInterface.class, url);
+
+    api.codecPost("request data");
+    assertThat(server.takeRequest()).hasPath("/");
+  }
+
+  @Test
+  public void testUrlPathConcatNoPathOnRequestLine() throws Exception {
+    server.enqueue(new MockResponse().setBody("response data"));
+
+    String url = "http://localhost:" + server.getPort() + "/";
+    TestInterface api = Feign.builder().target(TestInterface.class, url);
+
+    api.getNoPath();
+    assertThat(server.takeRequest()).hasPath("/");
+  }
+
+  @Test
+  public void testUrlPathConcatNoInitialSlashOnPath() throws Exception {
+    server.enqueue(new MockResponse().setBody("response data"));
+
+    String url = "http://localhost:" + server.getPort() + "/";
+    TestInterface api = Feign.builder().target(TestInterface.class, url);
+
+    api.getNoInitialSlashOnSlash();
+    assertThat(server.takeRequest()).hasPath("/api/thing");
+  }
+
+  @Test
+  public void testUrlPathConcatNoInitialSlashOnPathNoTrailingSlashOnUrl() throws Exception {
+    server.enqueue(new MockResponse().setBody("response data"));
+
+    String url = "http://localhost:" + server.getPort();
+    TestInterface api = Feign.builder().target(TestInterface.class, url);
+
+    api.getNoInitialSlashOnSlash();
+    assertThat(server.takeRequest()).hasPath("/api/thing");
+  }
+
   @Test
   public void testOverrideEncoder() throws Exception {
     server.enqueue(new MockResponse().setBody("response data"));
@@ -143,6 +187,11 @@ public class FeignBuilderTest {
   }
 
   interface TestInterface {
+    @RequestLine("GET")
+    Response getNoPath();
+
+    @RequestLine("GET api/thing")
+    Response getNoInitialSlashOnSlash();
 
     @RequestLine("POST /")
     Response codecPost(String data);