fix(core): interpolate {{value}} with the key for field: "@key"

packages/core/src/__tests__/linter.test.ts

@@ -1,4 +1,4 @@
-import { falsy, pattern, truthy } from '@stoplight/spectral-functions';
+import { enumeration, falsy, pattern, truthy } from '@stoplight/spectral-functions';
 import { DiagnosticSeverity } from '@stoplight/types';
 import { parse } from '@stoplight/yaml';
 import * as Parsers from '@stoplight/spectral-parsers';
@@ -30,6 +30,38 @@ describe('linter', () => {
     spectral = new Spectral();
   });
 
+  test('interpolates {{value}} with the property key for `field: "@key"` (#2922)', async () => {
+    spectral.setRuleset({
+      rules: {
+        rule1: {
+          given: '$.responses',
+          then: {
+            field: '@key',
+            function: enumeration,
+            functionOptions: { values: ['200', '400'] },
+          },
+        },
+      },
+    });
+
+    const document = new Document(
+      `responses:\n  "200":\n    description: "ok"\n  "404":\n    description: "not found"`,
+      Parsers.Yaml,
+    );
+
+    const results = await spectral.run(document);
+
+    expect(results).toEqual([
+      expect.objectContaining({
+        code: 'rule1',
+        // before the fix this interpolated to `Object{}` instead of the key
+        message: '"404" must be equal to one of the allowed values: "200", "400"',
+        severity: DiagnosticSeverity.Warning,
+        path: ['responses', '404'],
+      }),
+    ]);
+  });
+
   test('should demand some result', () => {
     return expect(spectral.run(new Document('123', Parsers.Json))).rejects.toThrow(
       'No ruleset has been defined. Have you called setRuleset()?',

packages/core/src/runner/lintNode.ts

@@ -46,11 +46,11 @@ export const lintNode = (context: IRunnerInternalContext, node: IGivenNode, rule
         const _fnContext = { ...fnContext };
         context.promises.push(
           targetResults.then(results =>
-            results === void 0 ? void 0 : processTargetResults(context, _fnContext, results),
+            results === void 0 ? void 0 : processTargetResults(context, _fnContext, results, then.field),
           ),
         );
       } else {
-        processTargetResults(context, fnContext, targetResults);
+        processTargetResults(context, fnContext, targetResults, then.field);
       }
     }
   }
@@ -60,6 +60,7 @@ function processTargetResults(
   context: IRunnerInternalContext,
   fnContext: RulesetFunctionContext & { rule: Rule },
   results: IFunctionResult[],
+  field: string | undefined,
 ): void {
   const { rule, path: targetPath } = fnContext;
   for (const result of results) {
@@ -70,7 +71,15 @@ function processTargetResults(
 
     const document = associatedItem?.document ?? context.documentInventory.document;
     const range = document.getRangeForJsonPath(path, true) ?? Document.DEFAULT_RANGE;
-    const value: unknown = path.length === 0 ? document.data : get(document.data, path);
+    // For `field: '@key'` the linted value is the property key itself, not the
+    // value stored at that path; reading the document at `path` would yield that
+    // value (e.g. an object), so `{{value}}` would interpolate to `Object{}`.
+    const value: unknown =
+      field === '@key' && result.path === void 0
+        ? path[path.length - 1]
+        : path.length === 0
+        ? document.data
+        : get(document.data, path);
 
     const vars: MessageVars = {
       property: