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diff --git a/src/java_tools/junitrunner/java/com/google/testing/junit/runner/sharding/ShardingEnvironment.java b/src/java_tools/junitrunner/java/com/google/testing/junit/runner/sharding/ShardingEnvironment.java
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+// Copyright 2010 The Bazel Authors. All Rights Reserved.
+//
+// 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 com.google.testing.junit.runner.sharding;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.io.Files;
+
+import java.io.File;
+import java.io.IOException;
+
+/**
+ * Utility class that encapsulates dependencies from sharding implementations
+ * on the test environment.  See http://bazel.io/docs/test-sharding.html for a
+ * list of all environment variables related to test sharding.
+ */
+public class ShardingEnvironment {
+
+  /**
+   * A singleton instance of ShardingEnvironment declared for convenience.
+   */
+  public static final ShardingEnvironment DEFAULT = new ShardingEnvironment();
+
+  /** Usage: -Dtest.sharding.strategy=round_robin */
+  private static final String TEST_SHARDING_STRATEGY = "test.sharding.strategy";
+
+  /**
+   * Return true iff the current test should be sharded.
+   */
+  public boolean isShardingEnabled() {
+    return System.getenv("TEST_TOTAL_SHARDS") != null;
+  }
+
+  /**
+   * Returns the 0-indexed test shard number, where
+   * 0 <= shard index < total shards.
+   * If the environment does not specify a test shard number, returns 0.
+   */
+  public int getShardIndex() {
+    String shardIndex = System.getenv("TEST_SHARD_INDEX");
+    return shardIndex == null ? 0 : Integer.parseInt(shardIndex);
+  }
+
+  /**
+   * Returns the total number of test shards, or 1 if not specified by the
+   * test environment.
+   */
+  public int getTotalShards() {
+    String totalShards = System.getenv("TEST_TOTAL_SHARDS");
+    return totalShards == null ? 1 : Integer.parseInt(totalShards);
+  }
+
+  /**
+   * Creates the shard file that is used to indicate that tests are
+   * being sharded.
+   */
+  public void touchShardFile() {
+    String shardStatusPath = System.getenv("TEST_SHARD_STATUS_FILE");
+    File shardFile = (shardStatusPath == null ? null : new File(shardStatusPath));
+    touchShardFile(shardFile);
+  }
+
+  @VisibleForTesting
+  static void touchShardFile(File shardFile) {
+    if (shardFile != null) {
+      try {
+        Files.touch(shardFile);
+      } catch (IOException e) {
+        throw new RuntimeException("Error writing shard file " + shardFile, e);
+      }
+    }
+  }
+
+  /**
+   * Returns the test sharding strategy optionally specified by the JVM flag
+   * {@link #TEST_SHARDING_STRATEGY}, which maps to the enums in
+   * {@link com.google.testing.junit.runner.sharding.ShardingFilters.ShardingStrategy}.
+   */
+  public String getTestShardingStrategy() {
+    return System.getProperty(TEST_SHARDING_STRATEGY);
+  }
+}