[Tests] improve version detection tests.

See #2128

Author: ljharb

package.json

@@ -38,6 +38,7 @@
     "eslint": "^3.0.0 || ^4.0.0 || ^5.0.0",
     "istanbul": "^0.4.5",
     "mocha": "^5.2.0",
+    "sinon": "^7.2.2",
     "typescript": "^3.2.2",
     "typescript-eslint-parser": "^20.1.1"
   },

tests/util/version.js

@@ -3,19 +3,27 @@
 
 const path = require('path');
 const assert = require('assert');
+const sinon = require('sinon');
 const versionUtil = require('../../lib/util/version');
 
 describe('Version', () => {
   const base = path.resolve(__dirname, '..', 'fixtures', 'version');
   let cwd;
+  let expectedErrorArgs = [];
 
   beforeEach(() => {
     cwd = process.cwd();
     process.chdir(base);
+    sinon.stub(console, 'error');
+    expectedErrorArgs = [];
   });
 
   afterEach(() => {
     process.chdir(cwd);
+
+    const actualArgs = console.error.args; // eslint-disable-line no-console
+    console.error.restore(); // eslint-disable-line no-console
+    assert.deepEqual(actualArgs, expectedErrorArgs);
   });
 
   describe('Detect version', () => {
@@ -29,6 +37,26 @@ describe('Version', () => {
 
     it('assumes latest version if react is not installed', () => {
       assert.equal(versionUtil.testReactVersion(context, '999.999.999'), true);
+
+      expectedErrorArgs = [
+        ['Warning: React version was set to "detect" in eslint-plugin-react settings, but the "react" package is not installed. Assuming latest React version for linting.']
+      ];
+    });
+  });
+
+  describe('string version', () => {
+    const context = {settings: {react: {version: '15.0', flowVersion: '1.2'}}};
+
+    it('works with react', () => {
+      assert.equal(versionUtil.testReactVersion(context, '0.14.0'), true);
+      assert.equal(versionUtil.testReactVersion(context, '15.0.0'), true);
+      assert.equal(versionUtil.testReactVersion(context, '16.0.0'), false);
+    });
+
+    it('works with flow', () => {
+      assert.equal(versionUtil.testFlowVersion(context, '1.1.0'), true);
+      assert.equal(versionUtil.testFlowVersion(context, '1.2.0'), true);
+      assert.equal(versionUtil.testFlowVersion(context, '1.3.0'), false);
     });
   });
 
@@ -39,12 +67,24 @@ describe('Version', () => {
       assert.equal(versionUtil.testReactVersion(context, '0.14.0'), true);
       assert.equal(versionUtil.testReactVersion(context, '15.0.0'), true);
       assert.equal(versionUtil.testReactVersion(context, '16.0.0'), false);
+
+      expectedErrorArgs = [
+        ['Warning: React version specified in eslint-plugin-react-settings must be a string; got “number”'],
+        ['Warning: React version specified in eslint-plugin-react-settings must be a string; got “number”'],
+        ['Warning: React version specified in eslint-plugin-react-settings must be a string; got “number”']
+      ];
     });
 
     it('works with flow', () => {
       assert.equal(versionUtil.testFlowVersion(context, '1.1.0'), true);
       assert.equal(versionUtil.testFlowVersion(context, '1.2.0'), true);
       assert.equal(versionUtil.testFlowVersion(context, '1.3.0'), false);
+
+      expectedErrorArgs = [
+        ['Warning: Flow version specified in eslint-plugin-react-settings must be a string; got “number”'],
+        ['Warning: Flow version specified in eslint-plugin-react-settings must be a string; got “number”'],
+        ['Warning: Flow version specified in eslint-plugin-react-settings must be a string; got “number”']
+      ];
     });
   });
 });