Add tests for when toBeTrue fails

package.json

@@ -3,7 +3,7 @@
   "version": "0.0.1",
   "description": "Additional Jest matchers",
   "main": "dist/index.js",
-  "files":[
+  "files": [
     "dist",
     "README.md",
     "LICENSE"
@@ -57,7 +57,8 @@
     "jest": "^21.2.1",
     "jest-each": "^0.3.1",
     "lint-staged": "^4.3.0",
-    "prettier": "^1.7.4"
+    "prettier": "^1.7.4",
+    "pretty-format": "^21.2.1"
   },
   "dependencies": {
     "chalk": "^2.2.0",
@@ -78,6 +79,9 @@
     "coveragePathIgnorePatterns": [
       "/node_modules/"
     ],
+    "snapshotSerializers": [
+      "pretty-format/build/plugins/convert_ansi.js"
+    ],
     "coverageThreshold": {
       "global": {
         "branches": 100,

src/matchers/toBeTrue/__snapshots__/index.test.js.snap

@@ -0,0 +1,18 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`.not.toBeTrue fails when given true 1`] = `
+"<dim>expect(</><red>received</><dim>).not.toBeTrue(</><dim>)</>
+
+Expected value to not be true:
+Received:
+  <red>true</>"
+`;
+
+exports[`toBeTrue fails when not given true 1`] = `
+"<dim>expect(</><red>received</><dim>).toBeTrue(</><dim>)</>
+
+Expected value to be true:
+  <green>true</>
+Received:
+  <red>false</>"
+`;

src/matchers/toBeTrue/index.test.js

@@ -2,17 +2,27 @@ import each from 'jest-each';
 
 import matcher from './';
 
-describe('toBeTrue', () => {
-  expect.extend(matcher);
+expect.extend(matcher);
 
+describe('toBeTrue', () => {
   it('passes when given true', () => {
     expect(true).toBeTrue();
   });
 
+  it('fails when not given true', () => {
+    expect(() => expect(false).toBeTrue()).toThrowErrorMatchingSnapshot();
+  });
+});
+
+describe('.not.toBeTrue', () => {
   each([[false], [''], [0], [{}], [[]], [() => {}], [undefined], [null], [NaN]]).it(
     'passes when not given true: %s',
     given => {
       expect(given).not.toBeTrue();
     }
   );
+
+  it('fails when given true', () => {
+    expect(() => expect(true).not.toBeTrue()).toThrowErrorMatchingSnapshot();
+  });
 });