feat: generate .npmrc with default pnpm option (#9956)

Add an .npmrc file so that when installing packages with pnpm, 
it is no longer necessary to pass the --shamefully-hoist flag.

flow-server/src/main/java/com/vaadin/flow/server/frontend/TaskRunNpmInstall.java

@@ -360,6 +360,13 @@ private void runNpmInstall() throws ExecutionFailedException {
                                 + "with npm by setting system variable -Dvaadin.pnpm.enable=false",
                         exception);
             }
+            try {
+                createNpmRcFile();
+            } catch (IOException exception) {
+                packageUpdater.log().warn(".npmrc generation failed; pnpm "
+                        + "package installation may require manaually passing "
+                        + "the --shamefully-hoist flag", exception);
+            }
         }
 
         List<String> executable;
@@ -482,6 +489,47 @@ private void createPnpmFile(String versionsPath) throws IOException {
         }
     }
 
+    /*
+     * Create an .npmrc file the project directory if there is none.
+     */
+    private void createNpmRcFile() throws IOException {
+        File npmrcFile = new File(packageUpdater.npmFolder.getAbsolutePath(),
+                ".npmrc");
+        boolean shouldWrite;
+        if (npmrcFile.exists()) {
+            List<String> lines = FileUtils.readLines(npmrcFile,
+                    StandardCharsets.UTF_8);
+            if (lines.stream().anyMatch(line -> line
+                    .contains("NOTICE: this is an auto-generated file"))) {
+                shouldWrite = true;
+            } else {
+                // Looks like this file was not generated by Vaadin
+                if (lines.stream()
+                        .noneMatch(line -> line.contains("shamefully-hoist"))) {
+                    String message = "Custom .npmrc file ({}) found in "
+                            + "project; pnpm package installation may "
+                            + "require passing the --shamefully-hoist flag";
+                    packageUpdater.log().info(message, npmrcFile);
+                }
+                shouldWrite = false;
+            }
+        } else {
+            shouldWrite = true;
+        }
+        if (shouldWrite) {
+            try (InputStream content = TaskRunNpmInstall.class
+                    .getResourceAsStream("/npmrc")) {
+                if (content == null) {
+                    throw new IOException(
+                            "Couldn't find template npmrc in the classpath");
+                }
+                FileUtils.copyInputStreamToFile(content, npmrcFile);
+                packageUpdater.log()
+                        .info("Generated pnpm configuration: '{}'", npmrcFile);
+            }
+        }
+    }
+
     private List<String> modifyPnpmFile(File generatedFile, String versionsPath)
             throws IOException {
         List<String> lines = FileUtils.readLines(generatedFile,

flow-server/src/main/resources/npmrc

@@ -0,0 +1,6 @@
+#
+# NOTICE: this is an auto-generated file
+#
+# This file sets the default parameters for manual `pnpm install`.
+#
+shamefully-hoist=true

flow-server/src/test/java/com/vaadin/flow/server/frontend/TaskRunPnpmInstallTest.java

@@ -19,6 +19,7 @@
 import java.io.IOException;
 import java.net.URI;
 import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
 
 import org.apache.commons.io.FileUtils;
 import org.hamcrest.CoreMatchers;
@@ -502,6 +503,63 @@ public void generateVersionsJson_versionsGeneratedFromPackageJson_containsBothDe
             versionsJson.toJson());
     }
 
+    @Test
+    public void runPnpmInstall_npmRcFileNotFound_newNpmRcFileIsGenerated()
+            throws IOException, ExecutionFailedException {
+        TaskRunNpmInstall task = createTask();
+        task.execute();
+
+        File npmRcFile = new File(getNodeUpdater().npmFolder, ".npmrc");
+        Assert.assertTrue(npmRcFile.exists());
+        String content = FileUtils.readFileToString(npmRcFile,
+                StandardCharsets.UTF_8);
+        Assert.assertTrue(content.contains("shamefully-hoist"));
+    }
+
+    @Test
+    public void runPnpmInstall_npmRcFileGeneratedByVaadinFound_npmRcFileIsGenerated()
+            throws IOException, ExecutionFailedException {
+        File oldNpmRcFile = new File(getNodeUpdater().npmFolder, ".npmrc");
+        // @formatter:off
+        String originalContent = "# NOTICE: this is an auto-generated file\n"
+                + "shamefully-hoist=true\n"
+                + "symlink=true\n";
+        // @formatter:on
+        FileUtils.writeStringToFile(oldNpmRcFile, originalContent,
+                StandardCharsets.UTF_8);
+
+        TaskRunNpmInstall task = createTask();
+        task.execute();
+
+        File newNpmRcFile = new File(getNodeUpdater().npmFolder, ".npmrc");
+        Assert.assertTrue(newNpmRcFile.exists());
+        String content = FileUtils.readFileToString(newNpmRcFile,
+                StandardCharsets.UTF_8);
+        Assert.assertTrue(content.contains("shamefully-hoist"));
+        Assert.assertFalse(content.contains("symlink=true"));
+    }
+
+    @Test
+    public void runPnpmInstall_customNpmRcFileFound_npmRcFileIsNotGenerated()
+            throws IOException, ExecutionFailedException {
+        File oldNpmRcFile = new File(getNodeUpdater().npmFolder, ".npmrc");
+        // @formatter:off
+        String originalContent = "# A custom npmrc file for my project\n"
+                + "symlink=true\n";
+        // @formatter:on
+        FileUtils.writeStringToFile(oldNpmRcFile, originalContent,
+                StandardCharsets.UTF_8);
+
+        TaskRunNpmInstall task = createTask();
+        task.execute();
+
+        File newNpmRcFile = new File(getNodeUpdater().npmFolder, ".npmrc");
+        Assert.assertTrue(newNpmRcFile.exists());
+        String content = FileUtils.readFileToString(newNpmRcFile,
+                StandardCharsets.UTF_8);
+        Assert.assertEquals(originalContent, content);
+    }
+
     @Override
     protected String getToolName() {
         return "pnpm";