fix: Allow for negation of segment match clauses. (#237)

Author: kinyoklion

packages/shared/sdk-server/__tests__/evaluation/Evaluator.segments.test.ts

@@ -110,6 +110,20 @@ describe('when evaluating user equivalent contexts for segments', () => {
     expect(res.detail.value).toBe(false);
   });
 
+  it('can negate a segment match op', async () => {
+    const segment = {
+      key: 'test',
+      included: ['foo'],
+      version: 1,
+    };
+    const evaluator = new Evaluator(basicPlatform, new TestQueries({ segments: [segment] }));
+    const flag = makeFlagWithSegmentMatch(segment);
+    flag.rules[0].clauses![0].negate = true;
+    const user = { key: 'bar' };
+    const res = await evaluator.evaluate(flag, Context.fromLDContext(user));
+    expect(res.detail.value).toBe(true);
+  });
+
   it.each([basicUser, basicSingleKindUser, basicMultiKindUser])(
     'matches segment with user who is both included and excluded',
     async (context) => {

packages/shared/sdk-server/src/evaluation/Evaluator.ts

@@ -17,7 +17,7 @@ import ErrorKinds from './ErrorKinds';
 import EvalResult from './EvalResult';
 import evalTargets from './evalTargets';
 import makeBigSegmentRef from './makeBigSegmentRef';
-import matchClauseWithoutSegmentOperations from './matchClause';
+import matchClauseWithoutSegmentOperations, { maybeNegate } from './matchClause';
 import matchSegmentTargets from './matchSegmentTargets';
 import { Queries } from './Queries';
 import Reasons from './Reasons';
@@ -296,7 +296,7 @@ export default class Evaluator {
         return new MatchError(errorResult);
       }
 
-      return new Match(match);
+      return new Match(maybeNegate(clause, match));
     }
     // This is after segment matching, which does not use the reference.
     if (!clause.attributeReference.isValid) {

packages/shared/sdk-server/src/evaluation/matchClause.ts

@@ -3,7 +3,7 @@ import { Context } from '@launchdarkly/js-sdk-common';
 import { Clause } from './data/Clause';
 import Operators from './Operations';
 
-function maybeNegate(clause: Clause, value: boolean): boolean {
+export function maybeNegate(clause: Clause, value: boolean): boolean {
   if (clause.negate) {
     return !value;
   }