Fix (not (not c1 c2)) to produce (or c1 c2) instead of just c1

Author: johanrd

lib/rules/template-no-negated-condition.js

@@ -96,6 +96,11 @@ module.exports = {
         const inverted = HELPER_INVERSIONS[helperName];
         if (inverted !== undefined) {
           if (inverted === null) {
+            if (inner.params.length > 1) {
+              // (not (not c1 c2)) -> (or c1 c2)
+              const paramsText = inner.params.map((p) => sourceCode.getText(p)).join(' ');
+              return `(or ${paramsText})`;
+            }
             // (not (not x)) -> just x
             return sourceCode.getText(inner.params[0]);
           }

tests/lib/rules/template-no-negated-condition.js

@@ -74,7 +74,7 @@ ruleTester.run('template-no-negated-condition', rule, {
     },
     {
       code: '<template>{{#if (not (not c1 c2))}}<img>{{/if}}</template>',
-      output: '<template>{{#if c1}}<img>{{/if}}</template>',
+      output: '<template>{{#if (or c1 c2)}}<img>{{/if}}</template>',
       errors: [{ messageId: 'negatedHelper' }],
     },
     {
@@ -263,7 +263,7 @@ hbsRuleTester.run('template-no-negated-condition', rule, {
     },
     {
       code: '{{#if (not (not c1 c2))}}<img>{{/if}}',
-      output: '{{#if c1}}<img>{{/if}}',
+      output: '{{#if (or c1 c2)}}<img>{{/if}}',
       errors: [{ message: 'Simplify unnecessary negation of helper.' }],
     },
     {