Merge pull request jsx-eslint#2336 from abhishekdev/handle-react-detect-errors

[Fix] Handle react version detect errors

Author: ljharb

lib/util/version.js

@@ -20,10 +20,12 @@ function detectReactVersion() {
     const react = require(reactPath); // eslint-disable-line import/no-dynamic-require
     return react.version;
   } catch (e) {
-    if (!warnedForMissingVersion && e.code === 'MODULE_NOT_FOUND') {
-      error('Warning: React version was set to "detect" in eslint-plugin-react settings, ' +
+    if (e.code === 'MODULE_NOT_FOUND') {
+      if (!warnedForMissingVersion) {
+        error('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.');
-      warnedForMissingVersion = true;
+        warnedForMissingVersion = true;
+      }
       return '999.999.999';
     }
     throw e;

tests/util/version.js

@@ -44,6 +44,15 @@ describe('Version', () => {
       ];
     });
 
+    it('warns only once for failure to detect react ', () => {
+      assert.equal(versionUtil.testReactVersion(context, '999.999.999'), true);
+      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.']
+      ];
+    });
+
     it('assumes latest version if flow-bin is not installed', () => {
       assert.equal(versionUtil.testFlowVersion(context, '999.999.999'), true);