fix PathUtil.getFileExtension - dot in the path must be not as ext

platform/core-api/src/com/intellij/util/PathUtil.java

@@ -1,18 +1,4 @@
-/*
- * Copyright 2000-2017 JetBrains s.r.o.
- *
- * 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.
- */
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package com.intellij.util;
 
 import com.intellij.openapi.application.PathManager;
@@ -73,9 +59,7 @@ public class PathUtil {
 
   @Nullable
   public static String getFileExtension(@NotNull String name) {
-    int index = name.lastIndexOf('.');
-    if (index < 0) return null;
-    return name.substring(index + 1);
+    return PathUtilRt.getFileExtension(name);
   }
 
   @NotNull

platform/platform-impl/src/org/jetbrains/io/FileResponses.kt

@@ -23,7 +23,7 @@ fun flushChunkedResponse(channel: Channel, isKeepAlive: Boolean) {
 
 object FileResponses {
   fun getContentType(path: String): String {
-    return fileExtToMimeType.getOrDefault(PathUtilRt.getFileExt(path), "application/octet-stream")
+    return PathUtilRt.getFileExtension(path)?.let { fileExtToMimeType.get(it) } ?: "application/octet-stream"
   }
 
   @JvmOverloads

platform/util-rt/src/com/intellij/util/PathUtilRt.java

@@ -26,16 +26,16 @@ public class PathUtilRt {
     return path.substring(getLastIndexOfPathSeparator(path, end) + 1, end);
   }
 
-  @NotNull
-  public static String getFileExt(@Nullable String path) {
+  @Nullable
+  public static String getFileExtension(@Nullable String path) {
     if (StringUtilRt.isEmpty(path)) {
-      return "";
+      return null;
     }
 
     int end = getEnd(path);
     int start = getLastIndexOfPathSeparator(path, end) + 1;
     int index = StringUtilRt.lastIndexOf(path, '.', Math.max(start, 0), end);
-    return index < 0 ? "" : path.substring(index + 1, end);
+    return index < 0 ? null : path.substring(index + 1, end);
   }
 
   private static int getEnd(@NotNull String path) {

platform/util/testSrc/com/intellij/util/PathUtilTest.java

@@ -22,10 +22,14 @@ public class PathUtilTest {
 
   @Test
   public void fileExt() {
-    assertThat(PathUtilRt.getFileExt("foo.html")).isEqualTo("html");
-    assertThat(PathUtilRt.getFileExt("foo.html/")).isEqualTo("html");
-    assertThat(PathUtilRt.getFileExt("/foo.html/")).isEqualTo("html");
-    assertThat(PathUtilRt.getFileExt("/bar/foo.html/")).isEqualTo("html");
+    assertThat(PathUtilRt.getFileExtension("foo.html")).isEqualTo("html");
+    assertThat(PathUtilRt.getFileExtension("foo.html/")).isEqualTo("html");
+    assertThat(PathUtilRt.getFileExtension("/foo.html/")).isEqualTo("html");
+    assertThat(PathUtilRt.getFileExtension("/bar/foo.html/")).isEqualTo("html");
+    assertThat(PathUtilRt.getFileExtension("")).isNull();
+    assertThat(PathUtilRt.getFileExtension("foo")).isNull();
+    assertThat(PathUtilRt.getFileExtension("foo.or.bar/bar")).isNull();
+    assertThat(PathUtilRt.getFileExtension("foo.")).isEmpty();
   }
 
   @Test