Improve usage errors

Add --help text, and print usage errors instead of crashing

MOE_MIGRATED_REVID=212338293

2 files changed, 17 insertions, 8 deletions

diff --git a/javatests/com/google/turbine/main/MainTest.java b/javatests/com/google/turbine/main/MainTest.java
index 9307cb0..654a89b 100644
--- a/javatests/com/google/turbine/main/MainTest.java
+++ b/javatests/com/google/turbine/main/MainTest.java
@@ -229,4 +229,17 @@ public class MainTest {
       assertThat(expected).hasMessageThat().contains("java.lang");
     }
   }
+
+  @Test
+  public void usage() throws IOException {
+    Path src = temporaryFolder.newFile("Test.java").toPath();
+    Files.write(src, "public class Test {}".getBytes(UTF_8));
+
+    try {
+      Main.compile(optionsWithBootclasspath().addSources(ImmutableList.of(src.toString())).build());
+      fail();
+    } catch (UsageException expected) {
+      assertThat(expected).hasMessageThat().contains("--output is required");
+    }
+  }
 }
diff --git a/javatests/com/google/turbine/options/TurbineOptionsTest.java b/javatests/com/google/turbine/options/TurbineOptionsTest.java
index f460da4..5953bac 100644
--- a/javatests/com/google/turbine/options/TurbineOptionsTest.java
+++ b/javatests/com/google/turbine/options/TurbineOptionsTest.java
@@ -80,7 +80,7 @@ public class TurbineOptionsTest {
     TurbineOptions options =
         TurbineOptionsParser.parse(Iterables.concat(BASE_ARGS, Arrays.asList(lines)));
 
-    assertThat(options.outputFile()).isEqualTo("out.jar");
+    assertThat(options.output()).hasValue("out.jar");
     assertThat(options.sourceJars())
         .containsExactly("sources1.srcjar", "sources2.srcjar")
         .inOrder();
@@ -223,13 +223,9 @@ public class TurbineOptionsTest {
   }
 
   @Test
-  public void failIfMissingExpectedArgs() throws Exception {
-    try {
-      TurbineOptions.builder().build();
-      fail();
-    } catch (NullPointerException e) {
-      assertThat(e).hasMessage("output must not be null");
-    }
+  public void tolerateMissingOutput() throws Exception {
+    TurbineOptions options = TurbineOptions.builder().build();
+    assertThat(options.output()).isEmpty();
   }
 
   @Test