feat: report error context and source excerpt

When failing to infer types instead of print error trace, report source except

#247

Author: KnisterPeter

Diff for: package.json

@@ -37,6 +37,7 @@
   "license": "MIT",
   "devDependencies": {
     "@knisterpeter/standard-tslint": "^1.3.0",
+    "@types/babel-generator": "6.7.14",
     "@types/chalk": "0.4.31",
     "@types/diff": "0.0.31",
     "@types/node": "7.0.5",
@@ -62,6 +63,7 @@
   },
   "dependencies": {
     "astq": "2.0.0",
+    "babel-generator": "6.23.0",
     "babylon": "6.16.1",
     "dts-dom": "0.1.15",
     "get-stdin": "5.0.1",

Diff for: src/types.ts

@@ -1,3 +1,4 @@
+import astToCode from 'babel-generator';
 import * as dom from 'dts-dom';
 import { propTypeQueryExpression, AstQuery } from './typings';
 
@@ -25,7 +26,12 @@ export function get(ast: AstQuery, propertyAst: any, propTypesName: string|undef
     }
   } catch (e) {
     console.error('Failed to infer PropType; Fallback to any');
-    console.error(e.stack);
+    if (e.loc) {
+      const src = astToCode(ast.ast).code;
+      console.error(`Line ${e.loc.start.line}: ${src.split('\n')[e.loc.start.line - 1]}`);
+    } else {
+      console.error(e.stack);
+    }
   }
   return {
     type: 'any',
@@ -159,7 +165,12 @@ function getShapeProperties(ast: AstQuery, input: any): any[] {
       ]
       /:init *
     `);
-    return res[0].properties;
+    if (res[0]) {
+      return res[0].properties;
+    }
+    const error = new Error('Failed to lookup shape properties');
+    (error as any).loc = input.loc;
+    throw error;
   }
   return input.properties;
 }

Diff for: src/typings.ts

@@ -5,6 +5,7 @@ import { InstanceOfResolver } from './index';
 import * as types from './types';
 
 export interface AstQuery {
+  ast: any;
   query(query: string): any[];
   querySubtree(subtree: any, query: string): any[];
 }
@@ -13,6 +14,7 @@ export function createTypings(moduleName: string|null, programAst: any,
     instanceOfResolver: InstanceOfResolver | undefined): string {
   const astq = new ASTQ();
   const ast = {
+    ast: programAst,
     query(query: string): any[] {
       return astq.query(programAst, query);
     },

Diff for: tests/error-reporting-test.ts

@@ -0,0 +1,34 @@
+import test from 'ava';
+
+import * as react2dts from '../src/index';
+
+const orignalConsoleError = console.error;
+
+test.beforeEach(t => {
+  console.error = function(): void {
+    const args = Array.prototype.slice.call(arguments);
+    if (!t.context.args) {
+      t.context.args = [];
+    }
+    t.context.args.push(args);
+  };
+});
+
+test.afterEach(() => {
+  console.error = orignalConsoleError;
+});
+
+test('In case of error during type inference the error information should be retained', t => {
+  react2dts.generateFromSource(null, `
+    import React from 'react';
+
+    export class Component extends React.Component {
+      static propTypes = {
+        someShape: React.PropTypes.shape(shape)
+      };
+    }
+  `);
+  const args = t.context.args.reduce((akku: any[], args: any[]) => [...akku, ...args], []);
+  const idx = args.indexOf('Line 6:     someShape: React.PropTypes.shape(shape)');
+  t.is(idx, 1);
+});