feat: support capturing code context from sourcesContent in the sourc…

…e map file (#959)

examples/node-dist/README.md

@@ -0,0 +1,7 @@
+# Node TypeScript distribution without original source
+
+This dir contains the dist files from ../node-typescript, and is suitable
+for testing source maps sourcesContent usage.
+
+This dir is currently only intended as support for rollbar.js test integration.
+It does not demonstrate the use of Rollbar.js.

src/server/parser.js

@@ -204,6 +204,9 @@ function readFileLines(filename, callback) {
 
 /* Older versions of node do not have fs.exists so we implement our own */
 function checkFileExists(filename, callback) {
+  if (stackTrace.sourceContent(filename)) {
+    return callback(true);
+  }
   if (fs.exists !== undefined) {
     fs.exists(filename, callback);
   } else {
@@ -228,17 +231,31 @@ function gatherContexts(frames, callback) {
 
     tempFileCache = {};
 
+    function cacheLines(filename, lines) {
+      // Cache this in a temp cache as well as the LRU cache so that
+      // we know we will have all of the necessary file contents for
+      // each filename in tempFileCache.
+      tempFileCache[filename] = lines;
+      cache.set(filename, lines);
+    }
+
     function gatherFileData(filename, callback) {
+      var sourceContent = stackTrace.sourceContent(filename);
+      if (sourceContent) {
+        try {
+          var lines = sourceContent.split('\n');
+          cacheLines(filename, lines);
+          return callback(null);
+        } catch (err) {
+          return callback(err);
+        }
+      }
       readFileLines(filename, function (err, lines) {
         if (err) {
           return callback(err);
         }
 
-        // Cache this in a temp cache as well as the LRU cache so that
-        // we know we will have all of the necessary file contents for
-        // each filename in tempFileCache.
-        tempFileCache[filename] = lines;
-        cache.set(filename, lines);
+        cacheLines(filename, lines);
 
         return callback(null);
       });

src/server/sourceMap/stackTrace.js

@@ -20,6 +20,9 @@ var fileContentsCache = {};
 // Maps a file path to a source map for that file
 var sourceMapCache = {};
 
+// Maps a file path to sourcesContent string
+var sourcesContentCache = {};
+
 // Regex for detecting source maps
 var reSourceMap = /^data:application\/json[^,]+base64,/;
 
@@ -111,6 +114,17 @@ function retrieveSourceMap(source) {
   };
 }
 
+function cacheSourceContent(sourceMap, originalSource, newSource) {
+  if (sourcesContentCache[newSource]) {
+    return;
+  }
+
+  // The sourceContentFor lookup needs the original source url as found in the
+  // map file. However the client lookup in sourcesContentCache will use
+  // a rewritten form of the url, hence originalSource and newSource.
+  sourcesContentCache[newSource] = sourceMap.map.sourceContentFor(originalSource, true);
+}
+
 exports.mapSourcePosition = function mapSourcePosition(position, diagnostic) {
   var sourceMap = sourceMapCache[position.source];
   if (!sourceMap) {
@@ -153,11 +167,17 @@ exports.mapSourcePosition = function mapSourcePosition(position, diagnostic) {
     // better to give a precise location in the compiled file than a vague
     // location in the original file.
     if (originalPosition.source !== null) {
+      var originalSource = originalPosition.source;
       originalPosition.source = supportRelativeURL(
         sourceMap.url, originalPosition.source);
+      cacheSourceContent(sourceMap, originalSource, originalPosition.source);
       return originalPosition;
     }
   }
 
   return position;
 }
+
+exports.sourceContent = function sourceContent(source) {
+  return sourcesContentCache[source];
+}

test/server.transforms.test.js

@@ -21,9 +21,9 @@ async function wait(ms) {
   });
 }
 
-async function throwInTypescriptFile(rollbar, callback) {
+async function throwInScriptFile(rollbar, filepath, callback) {
   setTimeout(function () {
-    var error = require('../examples/node-typescript/dist/index');
+    var error = require(filepath);
     error();
   }, 10);
   await wait(500);
@@ -256,8 +256,8 @@ vows.describe('transforms')
     }
   })
   .addBatch({
-    'handleItemWithError': {
-      'nodeSourceMaps': {
+    'nodeSourceMaps': {
+      'with original source present': {
         topic: function() {
           var Rollbar = new rollbar({
             accessToken: 'abc123',
@@ -267,9 +267,10 @@ vows.describe('transforms')
           var queue = Rollbar.client.notifier.queue;
           Rollbar.addItemStub = sinon.stub(queue, 'addItem');
 
-          throwInTypescriptFile(Rollbar, this.callback);
+          throwInScriptFile(Rollbar, '../examples/node-typescript/dist/index',
+            this.callback);
         },
-        'should map the stack': function(r) {
+        'should map the stack with context': function(r) {
           var addItem = r.addItemStub;
 
           assert.isTrue(addItem.called);
@@ -279,8 +280,15 @@ vows.describe('transforms')
             assert.equal(frame.lineno, 10);
             assert.equal(frame.colno, 22);
             assert.equal(frame.code, "  var error = <Error> new CustomError('foo');");
+            assert.equal(frame.context.pre[0], '    }');
+            assert.equal(frame.context.pre[1], '  }');
+            assert.equal(frame.context.pre[2],
+              '  // TypeScript code snippet will include `<Error>`');
+            assert.equal(frame.context.post[0], '  throw error;');
+            assert.equal(frame.context.post[1], '}');
 
-            var sourceMappingURLs = addItem.getCall(0).args[0].notifier.diagnostic.node_source_maps.source_mapping_urls;
+            var sourceMappingURLs = addItem.getCall(0).args[0].notifier.diagnostic
+              .node_source_maps.source_mapping_urls;
             var urls = Object.keys(sourceMappingURLs);
             assert.ok(urls[0].includes('index.js'));
             assert.ok(sourceMappingURLs[urls[0]].includes('index.js.map'));
@@ -295,8 +303,55 @@ vows.describe('transforms')
             assert.ok(sourceMappingURLs[urls[2]].includes('not found'));
           }
           addItem.reset();
+        }
+      }
+    }
+  })
+  .addBatch({
+    'nodeSourceMaps': {
+      'using sourcesContent': {
+        topic: function() {
+          var Rollbar = new rollbar({
+            accessToken: 'abc123',
+            captureUncaught: true,
+            nodeSourceMaps: true
+          });
+          var queue = Rollbar.client.notifier.queue;
+          Rollbar.addItemStub = sinon.stub(queue, 'addItem');
+
+          throwInScriptFile(Rollbar, '../examples/node-dist/index', this.callback);
         },
-      },
+        'should map the stack with context': function(r) {
+          var addItem = r.addItemStub;
+
+          assert.isTrue(addItem.called);
+          if (addItem.called) {
+            var frame = addItem.getCall(0).args[0].body.trace_chain[0].frames.pop();
+            assert.ok(frame.filename.includes('src/index.ts'));
+            assert.equal(frame.lineno, 10);
+            assert.equal(frame.colno, 22);
+            assert.equal(frame.code, "  var error = <Error> new CustomError('foo');");
+            assert.equal(frame.context.pre[0], '    }');
+            assert.equal(frame.context.pre[1], '  }');
+            assert.equal(frame.context.pre[2],
+              '  // TypeScript code snippet will include `<Error>`');
+            assert.equal(frame.context.post[0], '  throw error;');
+            assert.equal(frame.context.post[1], '}');
+
+            var sourceMappingURLs = addItem.getCall(0).args[0].notifier.diagnostic
+              .node_source_maps.source_mapping_urls;
+            var urls = Object.keys(sourceMappingURLs);
+            assert.ok(urls.length === 1);
+            assert.ok(urls[0].includes('index.js'));
+            assert.ok(sourceMappingURLs[urls[0]].includes('index.js.map'));
+          }
+          addItem.reset();
+        }
+      }
+    }
+  })
+  .addBatch({
+    'handleItemWithError': {
       'options': {
         'anything': {
           topic: function() {