doc, test: doc API design, add tests

JSAPI.md

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+# Draft of the JavaScript API
+
+This is currently a work in progress, expect the API to change significantly.
+Specifically, the APIs returning strings as results of inspection should return
+structured data instead for ease of use.
+
+```js
+class LLNode {
+  /**
+   * @param {string} dump path to the coredump
+   * @param {string} executable path to the node executable
+   * @returns {LLNode} an LLNode instance
+   */
+  static fromCoredump(dump, executable) {}
+
+  /**
+   * @returns {string} SBProcess information
+   */
+  getProcessInfo() {}
+
+  /**
+   * @typedef {object} Frame
+   * @property {string} function
+   * 
+   * @typedef {object} Thread
+   * @property {number} threadId
+   * @property {number} frameCount
+   * @property {Frame[]} frames
+   * 
+   * @typedef {object} Process
+   * @property {number} pid
+   * @property {string} state
+   * @property {number} threadCount
+   * @property {Thread[]} threads
+   * 
+   * @returns {Process} Process data
+   */
+  getProcessobject() {}
+
+  /**
+   * @typedef {object} HeapInstance
+   * @property {string} address
+   * @property {string} value
+   * 
+   * @typedef {object} HeapType
+   * @property {string} typeName
+   * @property {string} instanceCount
+   * @property {string} totalSize
+   * @property {LLNode} llnode
+   * @property {Iterator<HeapInstance>} instances
+   * 
+   * @returns {HeapType[]}
+   */
+  getHeapTypes() {}
+
+  /**
+   * TODO: rematerialize object
+   * @returns {HeapInstance}
+   */
+  getobjectAtAddress(address) {}
+}
+```

test/jsapi-test.js

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+'use strict';
+
+const fromCoredump = require('../').fromCoredump;
+
+const debug = process.env.TEST_LLNODE_DEBUG ?
+  console.log.bind(console) : () => { };
+
+const common = require('./common');
+const tape = require('tape');
+
+tape('llnode API', (t) => {
+  t.timeoutAfter(common.saveCoreTimeout);
+
+  // Use prepared core and executable to test
+  if (process.env.LLNODE_CORE && process.env.LLNODE_NODE_EXE) {
+    test(process.env.LLNODE_NODE_EXE, process.env.LLNODE_CORE, t);
+    t.end();
+  } else if (process.platform === 'linux') {
+    t.skip('No `process save-core` on linux');
+    t.end();
+  } else {
+    common.saveCore({
+      scenario: 'inspect-scenario.js'
+    }, (err) => {
+      t.error(err);
+      t.ok(true, 'Saved core');
+
+      test(process.execPath, common.core, t);
+      t.end();
+    });
+  }
+});
+
+function test(executable, core, t) {
+  debug('============= Loading ==============');
+  // Equivalent to lldb executable -c core
+  debug(`Loading core dump: ${core}, executable: ${executable}`);
+  const llnode = fromCoredump(core, executable);
+
+  verifySBProcess(llnode, t);
+  const typeMap = verifyBasicTypes(llnode, t);
+  const processType = verifyProcessType(typeMap, llnode, t);
+  verifyProcessInstances(processType, llnode, t);
+}
+
+function verifySBProcess(llnode, t) {
+  const processInfo = llnode.getProcessInfo();
+  debug('Process info', processInfo);
+  const procRe = new RegExp(
+    'SBProcess: pid = (\\d+), state = (\\w+), ' +
+    'threads = (\\d+), executable = .+');
+  const procMatch = processInfo.match(procRe);
+  t.ok(procMatch, 'SBProcess info should be formatted correctly');
+
+  const procObj = llnode.getProcessObject();
+  debug('Process object', procObj);
+  t.equal(procObj.pid, parseInt(procMatch[1]), 'SBProcess pid');
+  t.equal(procObj.state, procMatch[2], 'SBProcess state');
+  t.equal(procObj.threadCount, parseInt(procMatch[3]),
+    'SBProcess thread count');
+  t.ok(procObj.threadCount > 0,
+    'SBProcess should have more than one thread');
+  t.ok(Array.isArray(procObj.threads),
+    'processObject.threads should be an array');
+  t.equal(procObj.threads.length,
+    procObj.threadCount,
+    'processObject.threads should contain all the threads');
+
+  let i = 0;
+  for (const thread of procObj.threads) {
+    debug(`Thread ${i}:`, thread);
+    t.equal(thread.threadId, i++, 'thread.threadId');
+    t.ok(Array.isArray(thread.frames),
+      'thread.frames should be an array');
+    t.equal(thread.frameCount, thread.frames.length,
+      'thread.frames should contain all the frames');
+
+    for (const frame of thread.frames) {
+      debug(`  #`, frame);
+      t.ok(typeof frame.function === 'string',
+        'frame.function should be a string');
+    }
+  }
+}
+
+function verifyBasicTypes(llnode, t) {
+  debug('============= Heap Types ==============');
+  const heapTypes = llnode.getHeapTypes();
+  const basicTypes = [
+    // basic JS types
+    '(Array)', '(String)', 'Object', '(Object)', '(ArrayBufferView)',
+    // Node types
+    'process', 'NativeModule', 'console', 'TickObject'
+  ].sort();
+
+  const typeMap = new Map();
+  for (const item of heapTypes) {
+    if (basicTypes.indexOf(item.typeName) !== -1) {
+      typeMap.set(item.typeName, item);
+    }
+  }
+
+  const foundTypes = Array.from(typeMap.keys()).sort();
+  t.deepEqual(foundTypes, basicTypes,
+    'The heap should contain all the basic types');
+
+  return typeMap;
+}
+
+function verifyProcessType(typeMap, llnode, t) {
+  const processType = typeMap.get('process');
+
+  t.equal(processType.typeName, 'process',
+    'The typeName of process type should be "process"')
+  t.ok(processType.instanceCount > 0,
+    'There should be more than one process instances');
+  t.ok(processType.totalSize > 0,
+    'The process objects should have a non-zero size');
+  return processType;
+}
+
+function verifyProcessInstances(processType, llnode, t) {
+  // TODO: should be implemented as an iterator
+  let foundProcess = false;
+
+  const propRe = [
+    /.pid=<Smi: \d+>/,
+    /.platform=0x[0-9a-z]+:<String: ".+">/,
+    /.arch=0x[0-9a-z]+:<String: ".+">/,
+    /.version=0x[0-9a-z]+:<String: ".+">/,
+    /.versions=0x[0-9a-z]+:<Object: Object>/,
+    /.release=0x[0-9a-z]+:<Object: Object>/,
+    /.execPath=0x[0-9a-z]+:<String: ".+">/,
+    /.execArgv=0x[0-9a-z]+:<Array: length=\d+>/,
+    /.argv=0x[0-9a-z]+:<Array: length=\d+>/
+  ];
+
+  const visited = new Map();
+
+  for (const instance of processType.instances) {
+    t.ok(!visited.get(instance.address),
+      'should not duplicate instances');
+    visited.set(instance.address, instance.value);
+    t.deepEqual(
+      instance,
+      llnode.getObjectAtAddress(instance.address),
+      'instance should be the same as obtained from address')
+
+    if (propRe.every((re) => re.test(instance.value))) {
+      foundProcess = true;
+    }
+  }
+  t.ok(foundProcess, 'should find the process object');
+}