From 0b598a3a73ec5d26f6d6ecf9d8409ee246b45f80 Mon Sep 17 00:00:00 2001
From: Huanyi Xie <74809554+xiehuanyi@users.noreply.github.com>
Date: Sun, 11 Oct 2026 21:05:55 +0300
Subject: [PATCH 1/3] fix(csv-generate): allow numeric and null column return
 types

---
 packages/csv-generate/dist/cjs/index.d.cts |  4 +++-
 packages/csv-generate/dist/esm/index.d.ts  |  4 +++-
 packages/csv-generate/lib/index.d.ts       |  4 +++-
 packages/csv-generate/test/api.types.ts    | 15 +++++++++++++++
 4 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/packages/csv-generate/dist/cjs/index.d.cts b/packages/csv-generate/dist/cjs/index.d.cts
index 581ed32f4..909056478 100644
--- a/packages/csv-generate/dist/cjs/index.d.cts
+++ b/packages/csv-generate/dist/cjs/index.d.cts
@@ -14,7 +14,9 @@ export type ColumnsFunctionArgs = {
   options: Options;
   state: State;
 };
-export type ColumnsFunction = (args: ColumnsFunctionArgs) => string;
+export type ColumnsFunction = (
+  args: ColumnsFunctionArgs,
+) => string | number | null;
 
 export type State = {
   start_time: number;
diff --git a/packages/csv-generate/dist/esm/index.d.ts b/packages/csv-generate/dist/esm/index.d.ts
index 581ed32f4..909056478 100644
--- a/packages/csv-generate/dist/esm/index.d.ts
+++ b/packages/csv-generate/dist/esm/index.d.ts
@@ -14,7 +14,9 @@ export type ColumnsFunctionArgs = {
   options: Options;
   state: State;
 };
-export type ColumnsFunction = (args: ColumnsFunctionArgs) => string;
+export type ColumnsFunction = (
+  args: ColumnsFunctionArgs,
+) => string | number | null;
 
 export type State = {
   start_time: number;
diff --git a/packages/csv-generate/lib/index.d.ts b/packages/csv-generate/lib/index.d.ts
index 581ed32f4..909056478 100644
--- a/packages/csv-generate/lib/index.d.ts
+++ b/packages/csv-generate/lib/index.d.ts
@@ -14,7 +14,9 @@ export type ColumnsFunctionArgs = {
   options: Options;
   state: State;
 };
-export type ColumnsFunction = (args: ColumnsFunctionArgs) => string;
+export type ColumnsFunction = (
+  args: ColumnsFunctionArgs,
+) => string | number | null;
 
 export type State = {
   start_time: number;
diff --git a/packages/csv-generate/test/api.types.ts b/packages/csv-generate/test/api.types.ts
index 23f66e392..8a7918118 100644
--- a/packages/csv-generate/test/api.types.ts
+++ b/packages/csv-generate/test/api.types.ts
@@ -61,6 +61,21 @@ describe("API Types", function () {
       ];
     });
 
+    it("column functions can return numbers and null", function (next) {
+      generate(
+        {
+          length: 1,
+          encoding: "utf8",
+          columns: [() => 42, () => null],
+        },
+        (err, records) => {
+          if (err) return next(err);
+          (records as string).should.eql("42,");
+          next();
+        },
+      );
+    });
+
     it("delimiter", function () {
       const options: Options = {};
       options.delimiter = "|";

From e2818b7b603095742666d1cbfbe781f6608d949a Mon Sep 17 00:00:00 2001
From: Huanyi Xie <74809554+xiehuanyi@users.noreply.github.com>
Date: Mon, 12 Oct 2026 01:36:53 +0300
Subject: [PATCH 2/3] test(csv-generate): typecheck existing column option
 coverage

---
 packages/csv-generate/dist/cjs/index.d.cts        |  1 +
 packages/csv-generate/dist/esm/index.d.ts         |  1 +
 packages/csv-generate/lib/index.d.ts              |  1 +
 packages/csv-generate/test/api.types.ts           | 15 ---------------
 .../{options.columns.js => options.columns.ts}    | 10 ++++++----
 5 files changed, 9 insertions(+), 19 deletions(-)
 rename packages/csv-generate/test/{options.columns.js => options.columns.ts} (93%)

diff --git a/packages/csv-generate/dist/cjs/index.d.cts b/packages/csv-generate/dist/cjs/index.d.cts
index 909056478..8e0931a87 100644
--- a/packages/csv-generate/dist/cjs/index.d.cts
+++ b/packages/csv-generate/dist/cjs/index.d.cts
@@ -5,6 +5,7 @@ import * as stream from "stream";
 type Callback = (err?: Error, records?: unknown) => void;
 
 export class Generator extends stream.Readable {
+  end(): void;
   constructor(options?: Options);
 
   readonly options: Options;
diff --git a/packages/csv-generate/dist/esm/index.d.ts b/packages/csv-generate/dist/esm/index.d.ts
index 909056478..8e0931a87 100644
--- a/packages/csv-generate/dist/esm/index.d.ts
+++ b/packages/csv-generate/dist/esm/index.d.ts
@@ -5,6 +5,7 @@ import * as stream from "stream";
 type Callback = (err?: Error, records?: unknown) => void;
 
 export class Generator extends stream.Readable {
+  end(): void;
   constructor(options?: Options);
 
   readonly options: Options;
diff --git a/packages/csv-generate/lib/index.d.ts b/packages/csv-generate/lib/index.d.ts
index 909056478..8e0931a87 100644
--- a/packages/csv-generate/lib/index.d.ts
+++ b/packages/csv-generate/lib/index.d.ts
@@ -5,6 +5,7 @@ import * as stream from "stream";
 type Callback = (err?: Error, records?: unknown) => void;
 
 export class Generator extends stream.Readable {
+  end(): void;
   constructor(options?: Options);
 
   readonly options: Options;
diff --git a/packages/csv-generate/test/api.types.ts b/packages/csv-generate/test/api.types.ts
index 8a7918118..23f66e392 100644
--- a/packages/csv-generate/test/api.types.ts
+++ b/packages/csv-generate/test/api.types.ts
@@ -61,21 +61,6 @@ describe("API Types", function () {
       ];
     });
 
-    it("column functions can return numbers and null", function (next) {
-      generate(
-        {
-          length: 1,
-          encoding: "utf8",
-          columns: [() => 42, () => null],
-        },
-        (err, records) => {
-          if (err) return next(err);
-          (records as string).should.eql("42,");
-          next();
-        },
-      );
-    });
-
     it("delimiter", function () {
       const options: Options = {};
       options.delimiter = "|";
diff --git a/packages/csv-generate/test/options.columns.js b/packages/csv-generate/test/options.columns.ts
similarity index 93%
rename from packages/csv-generate/test/options.columns.js
rename to packages/csv-generate/test/options.columns.ts
index ab49d9aa4..548c256f3 100644
--- a/packages/csv-generate/test/options.columns.js
+++ b/packages/csv-generate/test/options.columns.ts
@@ -5,7 +5,7 @@ describe("Option `columns`", function () {
   it("as number", function (next) {
     this.timeout(1000000);
     let count = 0;
-    const data = [];
+    const data: Buffer[] = [];
     const generator = generate({ columns: 3 });
     generator.on("readable", () => {
       let d;
@@ -26,7 +26,7 @@ describe("Option `columns`", function () {
   it("as types", function (next) {
     this.timeout(1000000);
     let count = 0;
-    const data = [];
+    const data: Buffer[] = [];
     const generator = generate({ columns: ["int", "bool"], seed: 1 });
     generator.on("readable", () => {
       let d;
@@ -52,6 +52,7 @@ describe("Option `columns`", function () {
     try {
       generate({ columns: ["int", "bool", "invalid"] });
     } catch (err) {
+      if (!(err instanceof Error)) throw err;
       err.message.should.eql(
         'Invalid column type: got "invalid", default values are ["ascii","int","bool"]',
       );
@@ -61,7 +62,7 @@ describe("Option `columns`", function () {
   describe("user function", function () {
     it("accept string or null or number", function (next) {
       this.timeout(1000000);
-      const data = [];
+      const data: string[] = [];
       const generator = generate({
         length: 1,
         columns: [() => "a", () => null, () => 1],
@@ -81,6 +82,7 @@ describe("Option `columns`", function () {
 
     it("validate return argument", function (next) {
       this.timeout(1000000);
+      // @ts-expect-error Exercise runtime rejection of unsupported return values.
       const generator = generate({
         objectMode: true,
         columns: [() => ({})],
@@ -104,7 +106,7 @@ describe("Option `columns`", function () {
 
     it("validate arguments in objectMode", function (next) {
       this.timeout(1000000);
-      const data = [];
+      const data: unknown[] = [];
       const generator = generate({
         objectMode: true,
         length: 1,

From aaac3ac625bff87844e345227e59d587fdf0425e Mon Sep 17 00:00:00 2001
From: Huanyi Xie <74809554+xiehuanyi@users.noreply.github.com>
Date: Mon, 12 Oct 2026 01:49:22 +0300
Subject: [PATCH 3/3] test(csv-generate): keep error narrowing static

---
 packages/csv-generate/test/options.columns.ts | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/csv-generate/test/options.columns.ts b/packages/csv-generate/test/options.columns.ts
index 548c256f3..1b00d7e26 100644
--- a/packages/csv-generate/test/options.columns.ts
+++ b/packages/csv-generate/test/options.columns.ts
@@ -52,8 +52,7 @@ describe("Option `columns`", function () {
     try {
       generate({ columns: ["int", "bool", "invalid"] });
     } catch (err) {
-      if (!(err instanceof Error)) throw err;
-      err.message.should.eql(
+      (err as Error).message.should.eql(
         'Invalid column type: got "invalid", default values are ["ascii","int","bool"]',
       );
     }