Manage test dependencies with Bazel

Author: Marco Hunsicker

src/it/java/org/antlr/bazel/Dependencies.java

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+package org.antlr.bazel;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.nio.file.FileVisitResult;
+import java.nio.file.Files;
+import java.nio.file.LinkOption;
+import java.nio.file.Path;
+import java.nio.file.PathMatcher;
+import java.nio.file.Paths;
+import java.nio.file.SimpleFileVisitor;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+
+/**
+ * Fetches dependencies.
+ *
+ * @author  Marco Hunsicker
+ */
+class Dependencies
+{
+    private static final Map<Version, String[]> DEPENDENCIES = download();
+
+    /**
+     * Returns the ANTLR 4 dependencies.
+     *
+     * @return  the ANTLR 4 dependencies.
+     */
+    public static String[] antlr2()
+    {
+        return DEPENDENCIES.get(Version.V2);
+    }
+
+
+    /**
+     * Returns the ANTLR 3 dependencies.
+     *
+     * @return  the ANTLR 3 dependencies.
+     */
+    public static String[] antlr3()
+    {
+        return DEPENDENCIES.get(Version.V3);
+    }
+
+
+    /**
+     * Returns the ANTLR 2 dependencies.
+     *
+     * @return  the ANTLR 2 dependencies.
+     */
+    public static String[] antlr4()
+    {
+        return DEPENDENCIES.get(Version.V4);
+    }
+
+
+    private static Map<Version, String[]> download()
+    {
+        try
+        {
+            // the Bazel workspace root we use for dependency loading
+            Path workspace = Paths.get("src/it/resources/antlr/DownloadDependencies")
+                .toRealPath();
+            assertTrue(Files.exists(workspace));
+
+            Path base = getBaseDirectory(workspace);
+
+            Map<Version, String[]> deps = loadDependencies(base);
+
+            // if short-circuiting did not work, fetch the dependencies
+            if (deps.isEmpty())
+            {
+                fetchDependencies(workspace, base);
+                deps = loadDependencies(base);
+            }
+
+            assertFalse(deps.isEmpty());
+
+            return deps;
+        }
+        catch (Exception ex)
+        {
+            throw new IllegalStateException("Failed to load dependencies", ex);
+        }
+    }
+
+
+    private static void fetchDependencies(Path workspace, Path base) throws Exception
+    {
+        Process p = new ProcessBuilder().command("bazel", "fetch", "//...")
+            .directory(Paths.get(".").toRealPath().toFile())
+            .inheritIO()
+            .directory(workspace.toFile())
+            .start();
+        p.waitFor();
+
+        if (p.exitValue() != 0)
+        {
+            // cleanup if something went wrong to make short-circuiting reliable
+            Path external = base.resolve("external");
+
+            if (Files.exists(base))
+            {
+                Disk.delete(external);
+            }
+        }
+
+        assertEquals(0, p.exitValue());
+    }
+
+
+    private static Path getBaseDirectory(Path root) throws Exception
+    {
+        Process p = new ProcessBuilder().command("bazel", "info", "output_base")
+            .directory(Paths.get(".").toRealPath().toFile())
+            .redirectErrorStream(true)
+            .directory(root.toFile())
+            .start();
+
+        try (BufferedReader reader = new BufferedReader(
+                new InputStreamReader(p.getInputStream())))
+        {
+            StringBuilder buf = new StringBuilder();
+            String line = null;
+
+            while ((line = reader.readLine()) != null)
+            {
+                buf.append(line);
+            }
+
+            Path base = Paths.get(buf.toString());
+            assertTrue(Files.exists(base));
+
+            return base;
+        }
+        finally
+        {
+            p.waitFor();
+            assertEquals(0, p.exitValue());
+        }
+    }
+
+
+    private static Map<Version, String[]> loadDependencies(final Path base)
+        throws IOException
+    {
+        final Collection<String> deps2 = new ArrayList<>();
+        final Collection<String> deps3 = new ArrayList<>();
+        final Collection<String> deps4 = new ArrayList<>();
+
+        Path external = base.resolve("external");
+
+        if (Files.exists(external))
+        {
+            Files.walkFileTree(external, new SimpleFileVisitor<Path>()
+                {
+                    PathMatcher archives = base.getFileSystem()
+                        .getPathMatcher("glob:**/*.jar");
+                    PathMatcher antlr4 = base.getFileSystem()
+                        .getPathMatcher(
+                            "regex:.*(antlr4|antlr4-runtime|antlr-runtime|ST4|javax.json)-.*.jar");
+                    PathMatcher antlr3 = base.getFileSystem()
+                        .getPathMatcher("regex:.*/(antlr-3|antlr-runtime|ST4).*.jar");
+                    PathMatcher antlr2 = base.getFileSystem()
+                        .getPathMatcher("glob:**/antlr-2*.jar");
+
+                    @Override
+                    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs)
+                        throws IOException
+                    {
+                        if (archives.matches(file)
+                            && Files.isRegularFile(file, LinkOption.NOFOLLOW_LINKS))
+                        {
+                            if (antlr4.matches(file))
+                            {
+                                deps4.add(file.toString());
+                            }
+
+                            if (antlr3.matches(file))
+                            {
+                                deps3.add(file.toString());
+                            }
+
+                            if (antlr2.matches(file))
+                            {
+                                deps2.add(file.toString());
+                            }
+                        }
+
+                        return super.visitFile(file, attrs);
+                    }
+                });
+
+            Map<Version, String[]> result = new HashMap<>();
+            result.put(Version.V2, deps2.toArray(new String[deps2.size()]));
+            result.put(Version.V3, deps3.toArray(new String[deps3.size()]));
+            result.put(Version.V4, deps4.toArray(new String[deps4.size()]));
+
+            return result;
+        }
+
+        return Collections.emptyMap();
+    }
+}

src/it/java/org/antlr/bazel/Disk.java

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+package org.antlr.bazel;
+
+import java.io.IOException;
+import java.nio.file.CopyOption;
+import java.nio.file.FileVisitResult;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.SimpleFileVisitor;
+import java.nio.file.StandardCopyOption;
+import java.nio.file.attribute.BasicFileAttributes;
+
+
+/**
+ * Disk helper.
+ *
+ * @author  Marco Hunsicker
+ */
+class Disk
+{
+    private static final CopyOption[] ATTRIBUTES =
+        { StandardCopyOption.COPY_ATTRIBUTES, StandardCopyOption.REPLACE_EXISTING };
+
+    /** Creates a new Disk object. */
+    private Disk()
+    {
+        super();
+    }
+
+    /**
+     * Copies the given file or directory to the given destination.
+     *
+     * @param   path     the file or directory.
+     * @param   target   the target.
+     * @param   options  the options.
+     *
+     * @throws  IOException  if an I/O error occurred.
+     */
+    public static void copy(final Path path, final Path target, CopyOption... options)
+        throws IOException
+    {
+        final CopyOption[] opt = (options.length == 0) ? ATTRIBUTES : options;
+
+        if (Files.isDirectory(path))
+        {
+            Files.walkFileTree(path, new SimpleFileVisitor<Path>()
+                {
+                    @Override
+                    public FileVisitResult preVisitDirectory(Path dir,
+                        BasicFileAttributes attrs) throws IOException
+                    {
+                        Files.createDirectories(
+                            target.resolve(path.relativize(dir).toString()));
+
+                        return FileVisitResult.CONTINUE;
+                    }
+
+
+                    @Override
+                    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs)
+                        throws IOException
+                    {
+                        Files.copy(file,
+                            target.resolve(path.relativize(file).toString()),
+                            opt);
+
+                        return FileVisitResult.CONTINUE;
+                    }
+                });
+        }
+        else
+        {
+            Files.copy(path, target, opt);
+        }
+    }
+
+
+    /**
+     * Deletes the given file or directory.
+     *
+     * @param   path  the path.
+     *
+     * @throws  IOException  if an I/O error occurred.
+     */
+    public static void delete(Path path) throws IOException
+    {
+        if (Files.isDirectory(path))
+        {
+            Files.walkFileTree(path, DeleteVisitor.INSTANCE);
+        }
+        else if (Files.exists(path))
+        {
+            Files.delete(path);
+        }
+    }
+
+    private static class DeleteVisitor extends SimpleFileVisitor<Path>
+    {
+        public static final DeleteVisitor INSTANCE = new DeleteVisitor();
+
+        @Override
+        public FileVisitResult postVisitDirectory(Path dir, IOException cause)
+            throws IOException
+        {
+            Files.delete(dir);
+
+            return FileVisitResult.CONTINUE;
+        }
+
+
+        @Override
+        public FileVisitResult visitFile(Path file, BasicFileAttributes attrs)
+            throws IOException
+        {
+            Files.delete(file);
+
+            return FileVisitResult.CONTINUE;
+        }
+    }
+}