JTD empty values schema, fixes #1949 (#2191)

lib/vocabularies/jtd/values.ts

@@ -1,7 +1,7 @@
 import type {CodeKeywordDefinition, SchemaObject} from "../../types"
 import type {KeywordCxt} from "../../compile/validate"
 import {alwaysValidSchema, Type} from "../../compile/util"
-import {not, Name} from "../../compile/codegen"
+import {not, or, Name} from "../../compile/codegen"
 import {checkMetadata} from "./metadata"
 import {checkNullableObject} from "./nullable"
 import {typeError, _JTDTypeError} from "./error"
@@ -15,13 +15,16 @@ const def: CodeKeywordDefinition = {
   code(cxt: KeywordCxt) {
     checkMetadata(cxt)
     const {gen, data, schema, it} = cxt
-    if (alwaysValidSchema(it, schema)) return
     const [valid, cond] = checkNullableObject(cxt, data)
-    gen.if(cond)
-    gen.assign(valid, validateMap())
-    gen.elseIf(not(valid))
-    cxt.error()
-    gen.endIf()
+    if (alwaysValidSchema(it, schema)) {
+      gen.if(not(or(cond, valid)), () => cxt.error())
+    } else {
+      gen.if(cond)
+      gen.assign(valid, validateMap())
+      gen.elseIf(not(valid))
+      cxt.error()
+      gen.endIf()
+    }
     cxt.ok(valid)
 
     function validateMap(): Name | boolean {

spec/issues/1949_jtd_empty_values.spec.ts

@@ -0,0 +1,28 @@
+import _Ajv from "../ajv_jtd"
+import * as assert from "assert"
+
+describe("JTD values with empty schema (issue #1949)", () => {
+  const ajv = new _Ajv()
+
+  it("should correctly validate empty values form", () => {
+    const schema = {values: {}}
+    const validate = ajv.compile(schema)
+    assert.strictEqual(validate({prop1: 1, prop2: 2}), true)
+    assert.strictEqual(validate({}), true)
+    assert.strictEqual(validate(null), false)
+    assert.strictEqual(validate(1), false)
+    assert.strictEqual(validate("foo"), false)
+    assert.strictEqual(validate(undefined), false)
+  })
+
+  it("should correctly validate nullable empty values form", () => {
+    const schema = {values: {}, nullable: true}
+    const validate = ajv.compile(schema)
+    assert.strictEqual(validate({prop1: 1, prop2: 2}), true)
+    assert.strictEqual(validate({}), true)
+    assert.strictEqual(validate(null), true)
+    assert.strictEqual(validate(1), false)
+    assert.strictEqual(validate("foo"), false)
+    assert.strictEqual(validate(undefined), false)
+  })
+})

spec/issues/2001_jtd_only_optional_properties.spec.ts

@@ -1,7 +1,7 @@
 import _Ajv from "../ajv_jtd"
 import * as assert from "assert"
 
-describe("schema with optional/additional properties only", () => {
+describe("JTD schema with optional/additional properties only (issue #2001)", () => {
   const ajv = new _Ajv()
 
   it("should correctly serialize optional properties", () => {