test: parser/printer fuzz tests for expressions (tact-lang#1248)

.eslintignore

@@ -9,6 +9,7 @@ src/func/funcfiftlib.js
 **/grammar.ohm*.js
 src/grammar/next/grammar.ts
 jest.setup.js
+jest.globalSetup.js
 jest.teardown.js
 /docs
 version.build.ts

dev-docs/CONTRIBUTING.md

@@ -210,3 +210,23 @@ The project contains special TypeScript files with the `.build.ts` extension tha
 A typical example is [test/contracts.build.ts](https://github.com/tact-lang/tact/blob/132fe4ad7f030671d28740313b9d573fd8829684/src/test/contracts.build.ts) which builds contract tests.
 
 When adding new build or test scripts, make sure to use the `.build.ts` extension to keep them separate from the main compiler code.
+
+## Random AST Expression Generation
+
+To generate and inspect random Abstract Syntax Trees (ASTs), you can use the `yarn random-ast` command. This command generates a specified number of random Abstract Syntax Trees (ASTs) and pretty-prints them.
+
+Note: At the moment only Ast Expression will be generated
+
+### Usage
+
+`yarn random-ast <count>`
+
+Where `<count>` is the number of random expressions to generate.
+
+### Example
+
+`yarn random-ast 42`
+
+This will produce 42 random expressions and pretty-print them in the terminal.
+
+The implementation can be found in [random-ast.ts](../src/ast/random-ast.ts).

jest.config.js

@@ -6,7 +6,8 @@ module.exports = {
     testEnvironment: "node",
     testPathIgnorePatterns: ["/node_modules/", "/dist/"],
     maxWorkers: "8",
-    globalSetup: "./jest.setup.js",
+    globalSetup: "./jest.globalSetup.js",
+    setupFiles: ["./jest.setup.js"],
     globalTeardown: "./jest.teardown.js",
     snapshotSerializers: ["@tact-lang/ton-jest/serializers"],
 };

jest.globalSetup.js

@@ -0,0 +1,8 @@
+// eslint-disable-next-line @typescript-eslint/no-var-requires
+const coverage = require("@tact-lang/coverage");
+
+module.exports = async () => {
+    if (process.env.COVERAGE === "true") {
+        coverage.beginCoverage();
+    }
+};

jest.setup.js

@@ -1,7 +1,51 @@
-const coverage = require("@tact-lang/coverage");
+const fc = require("fast-check");
 
-module.exports = async () => {
-    if (process.env.COVERAGE === "true") {
-        coverage.beginCoverage();
+function sanitizeObject(
+    obj,
+    options = {
+        excludeKeys: [],
+        valueTransformers: {},
+    },
+) {
+    const { excludeKeys, valueTransformers } = options;
+
+    if (Array.isArray(obj)) {
+        return obj.map((item) => sanitizeObject(item, options));
+    } else if (obj !== null && typeof obj === "object") {
+        const newObj = {};
+        for (const [key, value] of Object.entries(obj)) {
+            if (!excludeKeys.includes(key)) {
+                const transformer = valueTransformers[key];
+                newObj[key] = transformer
+                    ? transformer(value)
+                    : sanitizeObject(value, options);
+            }
+        }
+        return newObj;
     }
-};
+    return obj;
+}
+
+fc.configureGlobal({
+    reporter: (log) => {
+        if (log.failed) {
+            const sanitizedCounterexample = sanitizeObject(log.counterexample, {
+                excludeKeys: ["id", "loc"],
+                valueTransformers: {
+                    value: (val) =>
+                        typeof val === "bigint" ? val.toString() : val,
+                },
+            });
+
+            const errorMessage = `
+      Property failed after ${log.numRuns} tests
+      Seed: ${log.seed}
+      Path: ${log.counterexamplePath}
+      Counterexample: ${JSON.stringify(sanitizedCounterexample, null, 0)}
+      Errors: ${log.error ? log.error : "Unknown error"}
+            `;
+
+            throw new Error(errorMessage);
+        }
+    },
+});

package.json

@@ -43,6 +43,7 @@
     "prepack": "pinst --disable",
     "postpack": "pinst --enable",
     "next-version": "ts-node version.build.ts",
+    "random-ast": "ts-node ./src/ast/random-ast.ts",
     "top10": "find . -type f -exec du -h {} + | sort -rh | head -n 10"
   },
   "files": [
@@ -55,7 +56,8 @@
     "!**/*.build.*",
     "!**/*.spec.js",
     "!**/*.spec.d.ts",
-    "!**/*.tsbuildinfo"
+    "!**/*.tsbuildinfo",
+    "!**/*.infra.ts"
   ],
   "main": "./dist/index.js",
   "bin": {
@@ -86,6 +88,7 @@
     "@ton/sandbox": "^0.24.0",
     "@ton/test-utils": "^0.5.0",
     "@tonstudio/pgen": "^0.0.1",
+    "@types/diff": "^7.0.0",
     "@types/glob": "^8.1.0",
     "@types/jest": "^29.5.12",
     "@types/json-bigint": "^1.0.4",
@@ -96,7 +99,9 @@
     "chalk": "4.1.2",
     "cross-env": "^7.0.3",
     "cspell": "^8.8.3",
+    "diff": "^7.0.0",
     "eslint": "^8.57.0",
+    "fast-check": "^3.23.2",
     "glob": "^8.1.0",
     "husky": "^9.1.5",
     "jest": "^29.3.1",

spell/cspell-list.txt

@@ -203,3 +203,4 @@ workchains
 xffff
 xtwitter
 привет
+letrec

src/ast/fuzz.spec.ts

@@ -0,0 +1,34 @@
+import fc from "fast-check";
+import { getParser } from "../grammar";
+import { eqExpressions, getAstFactory } from "../ast/ast-helpers";
+import { diffAstObjects, randomAstExpression } from "./random.infra";
+import { prettyPrint } from "./ast-printer";
+
+describe("Pretty Print Expressions", () => {
+    const maxDepth = 4;
+    const parser = getParser(getAstFactory(), "new");
+
+    it(`should parse AstExpression`, () => {
+        fc.assert(
+            fc.property(randomAstExpression(maxDepth), (generatedAst) => {
+                const prettyBefore = prettyPrint(generatedAst);
+
+                const parsedAst = parser.parseExpression(prettyBefore);
+                const prettyAfter = prettyPrint(parsedAst);
+
+                expect(prettyBefore).toBe(prettyAfter);
+                const actual = eqExpressions(generatedAst, parsedAst);
+                if (!actual) {
+                    diffAstObjects(
+                        generatedAst,
+                        parsedAst,
+                        prettyBefore,
+                        prettyAfter,
+                    );
+                }
+                expect(actual).toBe(true);
+            }),
+            { seed: 1, numRuns: 5000 },
+        );
+    });
+});

src/ast/random-ast.ts

@@ -0,0 +1,22 @@
+#!/usr/bin/env ts-node
+import fc from "fast-check";
+import { randomAstExpression } from "./random.infra";
+import { prettyPrint } from "./ast-printer";
+
+const args = process.argv.slice(2);
+if (args.length !== 1) {
+    console.error("Usage: yarn random-ast <count>");
+    process.exit(1);
+}
+
+const count = parseInt(args[0] ?? "", 10);
+if (isNaN(count) || count <= 0) {
+    console.error("Error: Count must be a positive integer");
+    process.exit(1);
+}
+
+fc.sample(randomAstExpression(4), count).forEach((expression, index) => {
+    console.log(`Expression ${index + 1}:`);
+    console.log(prettyPrint(expression));
+    console.log("-".repeat(80));
+});