In-repo test on src_dir, also fix

test/java_rules/BUILD

@@ -0,0 +1,14 @@
+# Test for java_library rules using src_dir
+java_library(
+    name = 'src_dir_lib',
+    src_dir = 'src',
+)
+
+java_test(
+    name = 'src_dir_test',
+    srcs = ['test/build/please/java/test/SrcDirTest.java'],
+    deps = [
+        ':src_dir_lib',
+        '//third_party/java:junit',
+    ],
+)

test/java_rules/src/build/please/java/test/SrcDirLib.java

@@ -0,0 +1,7 @@
+package build.please.java.test;
+
+public class SrcDirLib {
+  public static int WhatDoYouGetWhenYouMultiply(int a, int b) {
+    return a == 6 && b == 9 ? 42 : a * b;
+  }
+}

test/java_rules/test/build/please/java/test/SrcDirTest.java

@@ -0,0 +1,11 @@
+package build.please.java.test;
+
+import org.junit.Test;
+import static org.junit.Assert.assertEquals;
+
+public class SrcDirTest {
+  @Test
+  public void TestTheAnswer() {
+    assertEquals(42, SrcDirLib.WhatDoYouGetWhenYouMultiply(6, 9));
+  }
+}

tools/javac_worker/src/build/please/compile/JavaCompiler.java

@@ -16,7 +16,7 @@
 import javax.tools.ToolProvider;
 
 import build.please.worker.WorkerProto.BuildRequest;
-import build.please.worker.WorkerProto.BuildResponse;;
+import build.please.worker.WorkerProto.BuildResponse;
 
 public class JavaCompiler {
     /**
@@ -69,7 +69,7 @@ private void readStdin(byte[] b) throws IOException {
     /**
      * build handles building a single build rule.
      */
-    public BuildResponse build(BuildRequest request) {
+    public BuildResponse build(BuildRequest request) throws IOException {
         try {
             return reallyBuild(request);
         } catch (Exception ex) {
@@ -101,7 +101,7 @@ private BuildResponse reallyBuild(BuildRequest request) throws IOException {
         for (String src : request.getSrcsList()) {
             srcs.add(src.startsWith("/") ? src : request.getTempDir() + "/" + src);
         }
-        Iterable<? extends JavaFileObject> compilationUnits = fileManager.getJavaFileObjectsFromStrings(srcs);
+        Iterable<? extends JavaFileObject> compilationUnits;
         ArrayList<String> opts = new ArrayList<String>();
         opts.addAll(Arrays.asList(
             "-d", tmpDir,
@@ -114,6 +114,8 @@ private BuildResponse reallyBuild(BuildRequest request) throws IOException {
             FileFinder finder = new FileFinder(".java");
             Files.walkFileTree(new File(request.getTempDir() + "/" + request.getSrcs(0)).toPath(), finder);
             compilationUnits = fileManager.getJavaFileObjectsFromStrings(finder.getFiles());
+        } else {
+            compilationUnits = fileManager.getJavaFileObjectsFromStrings(srcs);
         }
         // Find any .jar files and add them to the classpath
         FileFinder finder = new FileFinder(".jar");