[ES|QL] generate function validation tests (#183343)

## Summary

Close #182390


### To test

You can test all aspects of the script by first making some changes to
`packages/kbn-esql-validation-autocomplete/src/validation/validation.test.ts`
- delete several tests from an existing function describe block ("block
1"—except don't choose "date_diff" since it has a bunch of custom tests)
- delete another function describe block completely ("block 2")
- change the expected result of several of the tests in a third function
describe block ("block 3")

Then, run `yarn maketests` from within
`packages/kbn-esql-validation-autocomplete`

**Expected result**
- Block 1 should have the deleted tests restored
- Block 2 should be restored entirely (though it may be moved in the
tests file)
- Block 3 should be untouched

### Checklist

- [x]
[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)
was added for features that require explanation or tutorials
- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

---------

Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>

.eslintrc.js

@@ -177,6 +177,7 @@ const DEV_PATTERNS = [
   'x-pack/performance/**/*',
   'src/setup_node_env/index.js',
   'src/cli/dev.js',
+  'packages/kbn-esql-validation-autocomplete/scripts/**/*',
 ];
 
 /** Restricted imports with suggested alternatives */

package.json

@@ -1683,6 +1683,7 @@
     "q": "^1.5.1",
     "raw-loader": "^3.1.0",
     "react-test-renderer": "^17.0.2",
+    "recast": "^0.23.7",
     "regenerate": "^1.4.0",
     "resolve": "^1.22.0",
     "rxjs-marbles": "^7.0.1",

packages/kbn-esql-validation-autocomplete/README.md

@@ -11,6 +11,8 @@ src
  | code_actions         // => the quick fixes service logic
  | definitions          // => static assets to define all components behaviour of a ES|QL query: commands, functions, etc...
  | validation           // => the validation logic
+
+scripts                 // => scripts used to manage the validation engine code
 ```
 
 ### Basic usage
@@ -45,12 +47,12 @@ import { validateQuery } from '@kbn/esql-validation-autocomplete';
 
 // define only the getSources callback
 const myCallbacks = {
-  getSources: async () => [{name: 'index', hidden: false}],
+  getSources: async () => [{ name: 'index', hidden: false }],
 };
 
 // ignore errors that might be triggered by the lack of some callbacks (i.e. "Unknown columns", etc...)
 const { errors, warnings } = await validateQuery(
-  "from index | stats 1 + avg(myColumn)",
+  'from index | stats 1 + avg(myColumn)',
   getAstAndSyntaxErrors,
   { ignoreOnMissingCallbacks: true },
   myCallbacks
@@ -161,12 +163,12 @@ For instance to show contextual information on Hover the `getAstContext` functio
 import { getAstAndSyntaxErrors } from '@kbn/esql-ast';
 import { getAstContext } from '@kbn/esql-validation-autocomplete';
 
-const queryString = "from index2 | stats 1 + avg(myColumn)";
-const offset = queryString.indexOf("avg");
+const queryString = 'from index2 | stats 1 + avg(myColumn)';
+const offset = queryString.indexOf('avg');
 
 const astContext = getAstContext(queryString, getAstAndSyntaxErrors(queryString), offset);
 
-if(astContext.type === "function"){
+if (astContext.type === 'function') {
   const fnNode = astContext.node;
   const fnDefinition = getFunctionDefinition(fnNode.name);
 
@@ -175,7 +177,6 @@ if(astContext.type === "function"){
 }
 ```
 
-
 ### How does it work
 
 The general idea of this package is to provide all ES|QL features on top of a custom compact AST definition (all data structure types defined in `@kbn/esql-ast`) which is designed to be resilient to many grammar changes.
@@ -211,9 +212,9 @@ The most complex case is the `expression` as it can cover a moltitude of cases.
 ### Adding new commands/options/functions/erc...
 
 To update the definitions:
+
 1. open either approriate definition file within the `definitions` folder and add a new entry to the relative array
-2. write new tests for validation and autocomplete
-  * if a new function is added tests are automatically generated fro both validation and autocomplete with some standard checks
-  * if a new function requires a new field types, make sure to add the new type to the initial part of the test file
-    * this will be automatically picked up by the test generator to produce new test cases
-  * if a new function requires a new type of test, make sure to write it manually
+2. if you are adding a function, run `yarn maketests` to add a set of fundamental validation tests for the new definition. If any of the suggested tests are wrong, feel free to correct them by hand. If it seems like a general problem, open an issue with the details so that we can update the generator code.
+3. write new tests for validation and autocomplete
+
+- if a new function requires a new type of test, make sure to write it manually

packages/kbn-esql-validation-autocomplete/package.json

@@ -1,7 +1,10 @@
 {
-    "name": "@kbn/esql-validation-autocomplete",
-    "version": "1.0.0",
-    "private": true,
-    "license": "SSPL-1.0 OR Elastic License 2.0",
-    "sideEffects": false
-  }
+  "name": "@kbn/esql-validation-autocomplete",
+  "version": "1.0.0",
+  "private": true,
+  "license": "SSPL-1.0 OR Elastic License 2.0",
+  "sideEffects": false,
+  "scripts": {
+    "maketests": "ts-node --transpileOnly ./scripts/generate_function_validation_tests.ts"
+  }
+}