From 25dc7c03cb1e3a9b167f31dd8fc804c97e29ec21 Mon Sep 17 00:00:00 2001
From: Mikhail Shustov <restrry@gmail.com>
Date: Mon, 24 Feb 2020 16:40:20 +0100
Subject: [PATCH] no sparse array by default. (#58212)

Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>
---
 .../src/types/array_type.test.ts              | 43 +++++++++++++++----
 .../kbn-config-schema/src/types/array_type.ts |  4 +-
 2 files changed, 37 insertions(+), 10 deletions(-)

diff --git a/packages/kbn-config-schema/src/types/array_type.test.ts b/packages/kbn-config-schema/src/types/array_type.test.ts
index 73661ef849cf..66b72096a593 100644
--- a/packages/kbn-config-schema/src/types/array_type.test.ts
+++ b/packages/kbn-config-schema/src/types/array_type.test.ts
@@ -85,6 +85,38 @@ test('fails if mixed types of content in array', () => {
   );
 });
 
+test('fails if sparse content in array', () => {
+  const type = schema.arrayOf(schema.string());
+  expect(type.validate([])).toEqual([]);
+  expect(() => type.validate([undefined])).toThrowErrorMatchingInlineSnapshot(
+    `"[0]: sparse array are not allowed"`
+  );
+});
+
+test('fails if sparse content in array if optional', () => {
+  const type = schema.arrayOf(schema.maybe(schema.string()));
+  expect(type.validate([])).toEqual([]);
+  expect(() => type.validate([undefined])).toThrowErrorMatchingInlineSnapshot(
+    `"[0]: sparse array are not allowed"`
+  );
+});
+
+test('fails if sparse content in array if nullable', () => {
+  const type = schema.arrayOf(schema.nullable(schema.string()));
+  expect(type.validate([])).toEqual([]);
+  expect(type.validate([null])).toEqual([null]);
+  expect(() => type.validate([undefined])).toThrowErrorMatchingInlineSnapshot(
+    `"[0]: sparse array are not allowed"`
+  );
+});
+
+test('fails for null values if optional', () => {
+  const type = schema.arrayOf(schema.maybe(schema.string()));
+  expect(() => type.validate([null])).toThrowErrorMatchingInlineSnapshot(
+    `"[0]: expected value of type [string] but got [null]"`
+  );
+});
+
 test('returns empty array if input is empty but type has default value', () => {
   const type = schema.arrayOf(schema.string({ defaultValue: 'test' }));
   expect(type.validate([])).toEqual([]);
@@ -95,16 +127,9 @@ test('returns empty array if input is empty even if type is required', () => {
   expect(type.validate([])).toEqual([]);
 });
 
-test('fails for null values if optional', () => {
-  const type = schema.arrayOf(schema.maybe(schema.string()));
-  expect(() => type.validate([null])).toThrowErrorMatchingInlineSnapshot(
-    `"[0]: expected value of type [string] but got [null]"`
-  );
-});
-
 test('handles default values for undefined values', () => {
-  const type = schema.arrayOf(schema.string({ defaultValue: 'foo' }));
-  expect(type.validate([undefined])).toEqual(['foo']);
+  const type = schema.arrayOf(schema.string(), { defaultValue: ['foo'] });
+  expect(type.validate(undefined)).toEqual(['foo']);
 });
 
 test('array within array', () => {
diff --git a/packages/kbn-config-schema/src/types/array_type.ts b/packages/kbn-config-schema/src/types/array_type.ts
index ad74f375588a..a0353e8348dd 100644
--- a/packages/kbn-config-schema/src/types/array_type.ts
+++ b/packages/kbn-config-schema/src/types/array_type.ts
@@ -31,7 +31,7 @@ export class ArrayType<T> extends Type<T[]> {
     let schema = internals
       .array()
       .items(type.getSchema().optional())
-      .sparse();
+      .sparse(false);
 
     if (options.minSize !== undefined) {
       schema = schema.min(options.minSize);
@@ -49,6 +49,8 @@ export class ArrayType<T> extends Type<T[]> {
       case 'any.required':
       case 'array.base':
         return `expected value of type [array] but got [${typeDetect(value)}]`;
+      case 'array.sparse':
+        return `sparse array are not allowed`;
       case 'array.parse':
         return `could not parse array value from [${value}]`;
       case 'array.min':