Emit a usage error if --output is not provided

PiperOrigin-RevId: 191961686

3 files changed, 62 insertions, 4 deletions

diff --git a/src/java_tools/import_deps_checker/java/com/google/devtools/build/importdeps/Main.java b/src/java_tools/import_deps_checker/java/com/google/devtools/build/importdeps/Main.java
index 6eed69e665..4d632d34e3 100644
--- a/src/java_tools/import_deps_checker/java/com/google/devtools/build/importdeps/Main.java
+++ b/src/java_tools/import_deps_checker/java/com/google/devtools/build/importdeps/Main.java
@@ -15,8 +15,9 @@ package com.google.devtools.build.importdeps;
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkState;
-import static com.google.common.io.Files.asCharSink;
+import static com.google.common.io.MoreFiles.asCharSink;
 
+import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableList;
 import com.google.devtools.common.options.Converter;
 import com.google.devtools.common.options.Option;
@@ -84,7 +85,7 @@ public class Main {
 
     @Option(
       name = "output",
-      defaultValue = "",
+      defaultValue = "null",
       category = "output",
       documentationCategory = OptionDocumentationCategory.UNCATEGORIZED,
       effectTags = {OptionEffectTag.UNKNOWN},
@@ -133,13 +134,14 @@ public class Main {
                 + ", classpath = "
                 + options.classpath);
         System.err.println(result);
-        asCharSink(options.output.toFile(), StandardCharsets.UTF_8).write(result);
+        asCharSink(options.output, StandardCharsets.UTF_8).write(result);
       }
     }
     System.exit(exitCode);
   }
 
-  private static Options parseCommandLineOptions(String[] args) throws IOException {
+  @VisibleForTesting
+  static Options parseCommandLineOptions(String[] args) throws IOException {
     OptionsParser optionsParser = OptionsParser.newOptionsParser(Options.class);
     optionsParser.setAllowResidue(false);
     optionsParser.enableParamsFileSupport(
@@ -148,6 +150,7 @@ public class Main {
     Options options = optionsParser.getOptions(Options.class);
 
     checkArgument(!options.inputJars.isEmpty(), "--input is required");
+    checkArgument(options.output != null, "--output is required");
     checkArgument(!options.bootclasspath.isEmpty(), "--bootclasspath_entry is required");
     return options;
   }
diff --git a/src/java_tools/import_deps_checker/javatests/com/google/devtools/build/importdeps/BUILD b/src/java_tools/import_deps_checker/javatests/com/google/devtools/build/importdeps/BUILD
index da4b1a9c55..19a70eb328 100644
--- a/src/java_tools/import_deps_checker/javatests/com/google/devtools/build/importdeps/BUILD
+++ b/src/java_tools/import_deps_checker/javatests/com/google/devtools/build/importdeps/BUILD
@@ -205,3 +205,14 @@ create_golden_test(
     rt_jar = "@local_jdk//:jre/lib/rt.jar",
     testdata_pkg = "//src/java_tools/import_deps_checker/javatests/com/google/devtools/build/importdeps/testdata",
 )
+
+java_test(
+    name = "MainTest",
+    srcs = ["MainTest.java"],
+    deps = [
+        "//third_party:junit4",
+        "//third_party:truth",
+        "//third_party/bazel/src/java_tools/import_deps_checker/java/com/google/devtools/build/importdeps:main",
+        "//third_party/bazel/src/test/java/com/google/devtools/build/lib/testutil",
+    ],
+)
diff --git a/src/java_tools/import_deps_checker/javatests/com/google/devtools/build/importdeps/MainTest.java b/src/java_tools/import_deps_checker/javatests/com/google/devtools/build/importdeps/MainTest.java
new file mode 100644
index 0000000000..e5bcb446e1
--- /dev/null
+++ b/src/java_tools/import_deps_checker/javatests/com/google/devtools/build/importdeps/MainTest.java
@@ -0,0 +1,44 @@
+// Copyright 2018 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.devtools.build.importdeps;
+
+import static com.google.common.truth.Truth.assertThat;
+import static com.google.devtools.build.lib.testutil.MoreAsserts.assertThrows;
+
+import java.nio.file.Path;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public final class MainTest {
+
+  @Rule public final TemporaryFolder tempFolder = new TemporaryFolder();
+
+  @Test
+  public void usage() throws Exception {
+    Path lib = tempFolder.newFile("lib.jar").toPath();
+    Path in = tempFolder.newFile("in.jar").toPath();
+    IllegalArgumentException thrown =
+        assertThrows(
+            IllegalArgumentException.class,
+            () ->
+                Main.parseCommandLineOptions(
+                    new String[] {"--classpath_entry", lib.toString(), "--input", in.toString()}));
+    assertThat(thrown).hasMessageThat().contains("--output");
+  }
+}