Update JacocoCoverageRunner

new blaze Java implementation sends the runtime jars encapsulated in a metadata
txt file, instead of listing them in the environment variable. The previous approach led to blaze crashing with an "Argument list too long" error.

PiperOrigin-RevId: 165155269

src/java_tools/junitrunner/java/com/google/testing/coverage/JacocoCoverageRunner.java

@@ -17,11 +17,9 @@
 import static java.nio.charset.StandardCharsets.UTF_8;
 
 import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.Function;
-import com.google.common.base.Splitter;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
-import com.google.common.collect.Iterables;
+import com.google.common.io.Files;
 import java.io.BufferedReader;
 import java.io.ByteArrayInputStream;
 import java.io.File;
@@ -33,6 +31,7 @@
 import java.io.Reader;
 import java.lang.reflect.Method;
 import java.net.URL;
+import java.util.ArrayList;
 import java.util.Enumeration;
 import java.util.HashSet;
 import java.util.List;
@@ -293,10 +292,9 @@ private static String getUniquePath(String pathTemplate, String suffix) throws I
   }
 
   public static void main(String[] args) throws Exception {
-    final String metadataJar = System.getenv("JACOCO_METADATA_JAR");
-    String newMetadataJarsString = System.getenv("JACOCO_METADATA_JARS");
-    final List<String> newMetadataJars =
-        newMetadataJarsString == null ? null : Splitter.on(':').splitToList(newMetadataJarsString);
+    final String metadataFile = System.getenv("JACOCO_METADATA_JAR");
+    final boolean isNewImplementation = metadataFile.endsWith(".txt");
+    final String javaRunfilesRoot = System.getenv("JACOCO_JAVA_RUNFILES_ROOT");
 
     final String coverageReportBase = System.getenv("JAVA_COVERAGE_FILE");
 
@@ -354,22 +352,20 @@ public void run() {
                     dataInputStream = new ByteArrayInputStream(new byte[0]);
                   }
 
-                  if (metadataJar != null) {
-                    // Disable coverage in this case. The build system should report an error or
-                    // warning if this happens. It's too late at this point.
-                    new JacocoCoverageRunner(dataInputStream, coverageReport, new File(metadataJar))
-                        .create();
-                  } else if (newMetadataJars != null){
-                    File[] metadataJars = Iterables.toArray(
-                        Iterables.transform(newMetadataJars, new Function<String, File>() {
-                          @Override
-                          public File apply(String input) {
-                            return new File(input);
-                          }
-                        }), File.class);
-                    new JacocoCoverageRunner(true, dataInputStream, coverageReport, metadataJars)
-                        .create();
+                  File[] metadataJars;
+                  if (isNewImplementation) {
+                    List<String> metadataFiles = Files.readLines(new File(metadataFile), UTF_8);
+                    List<File> convertedMetadataFiles = new ArrayList<>();
+                    for (String metadataFile : metadataFiles) {
+                      convertedMetadataFiles.add(new File(javaRunfilesRoot + metadataFile));
+                    }
+                    metadataJars = convertedMetadataFiles.toArray(new File[0]);
+                  } else {
+                    metadataJars = new File[] {new File(metadataFile)};
                   }
+
+                  new JacocoCoverageRunner(
+                      isNewImplementation, dataInputStream, coverageReport, metadataJars).create();
                 } catch (IOException e) {
                   e.printStackTrace();
                   Runtime.getRuntime().halt(1);
@@ -384,7 +380,7 @@ public File apply(String input) {
     // We'd share the same limitation if the system under test uses shutdown hooks internally, as
     // there's no way to collect coverage data on that code.
     String mainClass =
-        newMetadataJars == null ? getMainClass(metadataJar) : System.getenv("JACOCO_MAIN_CLASS");
+        isNewImplementation ? System.getenv("JACOCO_MAIN_CLASS") : getMainClass(metadataFile);
     Method main = Class.forName(mainClass).getMethod("main", String[].class);
     main.invoke(null, new Object[] {args});
   }