chore: add check_deps script (#3182)

This will be used to disallow cross-directory imports,
for example from impl to rpc.

package.json

@@ -29,7 +29,8 @@
     "typecheck-tests": "tsc -p ./test/",
     "roll-browser": "node utils/roll_browser.js",
     "jest": "jest",
-    "coverage": "node test/jest/checkCoverage.js"
+    "coverage": "node test/jest/checkCoverage.js",
+    "check-deps": "node utils/check_deps.js"
   },
   "author": {
     "name": "Microsoft Corporation"

utils/check_deps.js

@@ -0,0 +1,62 @@
+#!/usr/bin/env node
+/**
+ * Copyright 2019 Google Inc. All rights reserved.
+ * Modifications copyright (c) Microsoft Corporation.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+const ts = require('typescript');
+const path = require('path');
+const Source = require('./doclint/Source');
+
+async function checkDeps() {
+  const root = path.normalize(path.join(__dirname, '..'));
+  const src = path.normalize(path.join(__dirname, '..', 'src'));
+  const sources = await Source.readdir(src);
+  const program = ts.createProgram({
+    options: {
+      allowJs: true,
+      target: ts.ScriptTarget.ESNext,
+      strict: true,
+    },
+    rootNames: sources.map(source => source.filePath()),
+  });
+  const sourceFiles = program.getSourceFiles();
+  const errors = [];
+  sourceFiles.filter(x => !x.fileName.includes('node_modules')).map(x => visit(x, x.fileName));
+  for (const error of errors)
+    console.log(error);
+  process.exit(errors.length ? 1 : 0);
+
+  function visit(node, fileName) {
+    if (ts.isImportDeclaration(node) && ts.isStringLiteral(node.moduleSpecifier)) {
+      const importName = node.moduleSpecifier.text;
+      const importPath = path.resolve(path.dirname(fileName), importName);
+      if (!allowImport(fileName, importPath))
+        errors.push(`Disallowed import from ${path.relative(root, fileName)} to ${path.relative(root, importPath)}`);
+    }
+    ts.forEachChild(node, x => visit(x, fileName));
+  }
+
+  function allowImport(from, to) {
+    const rpc = path.join('src', 'rpc');
+    if (!from.includes(rpc) && to.includes(rpc))
+      return false;
+    if (from.includes(rpc) && !to.includes(rpc))
+      return false;
+    return true;
+  }
+}
+
+checkDeps();