feat: improve oneOf error reporting, #573

lib/dot/errors.def

@@ -182,7 +182,7 @@
   _limitProperties:"{ limit: {{=$schemaValue}} }",
   multipleOf:      "{ multipleOf: {{=$schemaValue}} }",
   not:             "{}",
-  oneOf:           "{}",
+  oneOf:           "{ passingSchemas: {{=$passingSchemas}} }",
   pattern:         "{ pattern: {{#def.schemaValueQS}} }",
   patternGroups:   "{ reason: '{{=$reason}}', limit: {{=$limit}}, pattern: '{{=it.util.escapeQuotes($pgProperty)}}' }",
   propertyNames:   "{ propertyName: '{{=$invalidName}}' }",

lib/dot/oneOf.jst

@@ -3,11 +3,17 @@
 {{# def.setupKeyword }}
 {{# def.setupNextLevel }}
 
-var {{=$errs}} = errors;
-var prevValid{{=$lvl}} = false;
-var {{=$valid}} = false;
+{{
+  var $currentBaseId = $it.baseId
+    , $prevValid = 'prevValid' + $lvl
+    , $passingSchemas = 'passingSchemas' + $lvl;
+}}
+
+var {{=$errs}} = errors
+  , {{=$prevValid}} = false
+  , {{=$valid}} = false
+  , {{=$passingSchemas}} = null;
 
-{{ var $currentBaseId = $it.baseId; }}
 {{# def.setCompositeRule }}
 
 {{~ $schema:$sch:$i }}
@@ -24,13 +30,17 @@ var {{=$valid}} = false;
   {{?}}
 
   {{? $i }}
-    if ({{=$nextValid}} && prevValid{{=$lvl}})
+    if ({{=$nextValid}} && {{=$prevValid}}) {
       {{=$valid}} = false;
-    else {
+      {{=$passingSchemas}} = [{{=$passingSchemas}}, {{=$i}}];
+    } else {
     {{ $closingBraces += '}'; }}
   {{?}}
 
-    if ({{=$nextValid}}) {{=$valid}} = prevValid{{=$lvl}} = true;
+    if ({{=$nextValid}}) {
+      {{=$valid}} = {{=$prevValid}} = true;
+      {{=$passingSchemas}} = {{=$i}};
+    }
 {{~}}
 
 {{# def.resetCompositeRule }}

spec/errors.spec.js

@@ -539,6 +539,39 @@ describe('Validation errors', function () {
         validate(1.5) .should.equal(true);
       }
     });
+
+    it('should return passing schemas in error params', function() {
+      var schema = {
+        oneOf: [
+          { type: 'number' },
+          { type: 'integer' },
+          { const: 1.5 }
+        ]
+      };
+
+      test(ajv);
+      test(fullAjv);
+
+      function test(_ajv) {
+        var validate = _ajv.compile(schema);
+        validate(1) .should.equal(false);
+        var err = validate.errors.pop();
+        err.keyword .should.equal('oneOf');
+        err.params .should.eql({passingSchemas: [0, 1]});
+
+        validate(1.5) .should.equal(false);
+        err = validate.errors.pop();
+        err.keyword .should.equal('oneOf');
+        err.params .should.eql({passingSchemas: [0, 2]});
+
+        validate(2.5) .should.equal(true);
+
+        validate('foo') .should.equal(false);
+        err = validate.errors.pop();
+        err.keyword .should.equal('oneOf');
+        err.params .should.eql({passingSchemas: null});
+      }
+    });
   });