downlevel in a loop, until stabilised

Workaround for sandersn/downlevel-dts#50

downlevel.js

@@ -0,0 +1,42 @@
+const childProcess = require("child_process");
+const fs = require("fs");
+
+const main = () => {
+    const tempFolder = `temp/downlevel`;
+    childProcess.execSync(`rm -rf ${tempFolder}`, { stdio: "inherit" });
+    fs.mkdirSync(`${tempFolder}`, { recursive: true });
+    childProcess.execSync(`cp -r dist ${tempFolder}/0`, { stdio: "inherit" });
+    for (let i = 1; i < 10; i++) {
+        const [prev, next] = [i - 1, i].map(n => `${tempFolder}/${n}`);
+        console.log(`downleveling into ${next}`);
+        childProcess.execSync(`downlevel-dts ${prev} ${next} --to=3.4`, { stdio: "inherit" });
+
+        const [prevResult, nextResult] = [prev, next].map(folder =>
+            fs.readFileSync(`${folder}/generated/interface.d.ts`).toString()
+        );
+        if (prevResult === nextResult) {
+            if (i <= 2) {
+                throw new Error(
+                    `downleveling stabilised too quickly, maybe https://github.com/sandersn/downlevel-dts/issues/50 has been fixed?`
+                );
+            }
+            const target = `ts34/dist`;
+            console.log(`downleveling stabilised after ${i} iterations, copying to ${target}.`);
+            childProcess.execSync(`rm -rf ${target}`, { stdio: "inherit" });
+            fs.mkdirSync("ts34", { recursive: true });
+            childProcess.execSync(`cp -r ${next} ${target}`, { stdio: "inherit" });
+            console.log(`Replacing push implementation incompatible with typescript < 4`);
+            childProcess.execSync(`mv ${target}/push.ts34.d.ts ${target}/push.d.ts`, { stdio: "inherit" });
+            console.log(`Running old version of typescript on output`);
+            childProcess.execSync(`npx -p [email protected] tsc ts34/dist/index.d.ts --noEmit`, { stdio: "inherit" });
+            console.log(`Removing temporary files`);
+            childProcess.execSync(`rm -rf ${tempFolder}`, { stdio: "inherit" });
+            console.log("Done.");
+            return;
+        }
+        console.log({ prev, next }, "had different outputs, running again");
+    }
+    throw new Error(`Downleveling failed!`);
+};
+
+main();

package.json

@@ -36,7 +36,7 @@
     "clean": "del-cli 'dist' 'ts34' 'src/generated' 'test/generated'",
     "codegen": "ts-node codegen/generate-schema && ts-node codegen/generate-client && ts-node codegen/generate-tests",
     "compile": "tsc -p tsconfig.lib.json",
-    "postcompile": "downlevel-dts dist ts34/dist --to=3.4 && mv ts34/dist/push.ts34.d.ts ts34/dist/push.d.ts",
+    "postcompile": "node downlevel",
     "coverage": "yarn test --coverage",
     "coveralls": "yarn coverage --coverageReporters=text-lcov | coveralls",
     "lint": "eslint --max-warnings 0 --ext .ts,.js,.md .",