Small fixes and enable coverage output in the console

jest.config.js

@@ -2,7 +2,12 @@
 
 module.exports = {
   "collectCoverage": true,
-  "coverageReporters": ["lcov"],
+  "coverageReporters": ["lcov", "text"],
+  "coveragePathIgnorePatterns": [
+    "<rootDir>/node_modules/",
+    "<rootDir>/lib/parser.js",
+    "<rootDir>/test",
+  ],
   "roots": [
     "<rootDir>/test",
   ],

lib/compiler/asts.js

@@ -21,6 +21,8 @@ const asts = {
       }
     }
 
+    // istanbul ignore next Presence of rules checked using another approach that not involve this function
+    // Any time when it is called the rules always exist
     return -1;
   },
 

lib/compiler/passes/generate-js.js

@@ -134,6 +134,7 @@ function generateJS(ast, options) {
                   + ")";
         }
         case "any": return "peg$anyExpectation()";
+        // istanbul ignore next Because we never generate expectation type we cannot reach this branch
         default: throw new Error("Unknown expectation type (" + JSON.stringify(e) + ")");
       }
     }
@@ -525,6 +526,7 @@ function generateJS(ast, options) {
             ip++;
             break;
 
+          // istanbul ignore next Because we never generate invalid bytecode we cannot reach this branch
           default:
             throw new Error("Invalid opcode: " + bc[ip] + ".");
         }
@@ -594,6 +596,7 @@ function generateJS(ast, options) {
       "",
       "function peg$SyntaxError(message, expected, found, location) {",
       "  var self = Error.call(this, message);",
+      "  // istanbul ignore next Check is a necessary evil to support older environments",
       "  if (Object.setPrototypeOf) {",
       "    Object.setPrototypeOf(self, peg$SyntaxError.prototype);",
       "  }",

lib/grammar-error.js

@@ -2,6 +2,7 @@
 
 // See: https://github.com/Microsoft/TypeScript-wiki/blob/master/Breaking-Changes.md#extending-built-ins-like-error-array-and-map-may-no-longer-work
 // This is roughly what typescript generates, it's not called after super(), where it's needed.
+// istanbul ignore next This is a special black magic that cannot be covered everywhere
 const setProtoOf = Object.setPrototypeOf
   || ({ __proto__: [] } instanceof Array
       && function(d, b) {

test/cli/run.spec.ts

@@ -184,12 +184,12 @@ Options:
   -h, --help                       display help for command
 `;
 
-    await expect(await exec({
+    await expect(exec({
       args: ["-h"],
-    })).toBe(HELP);
-    await expect(await exec({
+    })).resolves.toBe(HELP);
+    await expect(exec({
       args: ["--help"],
-    })).toBe(HELP);
+    })).resolves.toBe(HELP);
   });
 
   it("rejects invalid options", async() => {

test/unit/compiler.spec.js

@@ -21,7 +21,7 @@ describe("Peggy compiler", () => {
     })).to.throw('Unknown start rule "bar"');
   });
 
-  it("checks ouput type", () => {
+  it("checks output type", () => {
     const ast = parser.parse("foo='1'");
     expect(compiler.compile(ast, compiler.passes, {
       output: "source",