fix(csv-generate): stream object records independently of column values

packages/csv-generate/lib/api/read.js

@@ -55,12 +55,10 @@ const read = (options, state, size, push, close) => {
     }
     // Obtain record length
     if (options.objectMode) {
-      recordLength = 0;
-      // recordLength is currently equal to the number of columns
-      // This is wrong and shall equal to 1 record only
-      for (const column of record) {
-        recordLength += column.length;
-      }
+      // Let the stream request each record independently of its column values.
+      state.count_created++;
+      push(record);
+      return;
     } else {
       // Stringify the record
       record =

packages/csv-generate/test/api.sync.js

@@ -31,4 +31,17 @@ describe("api sync", function () {
     const data = generate({ length: 1000, objectMode: true });
     data.length.should.eql(1000);
   });
+
+  it("preserves supported column values in objectMode", function () {
+    const data = generate({
+      length: 3,
+      objectMode: true,
+      columns: [() => "value", () => null, () => 42, () => ""],
+    });
+    data.should.eql([
+      ["value", null, 42, ""],
+      ["value", null, 42, ""],
+      ["value", null, 42, ""],
+    ]);
+  });
 });

packages/csv-generate/test/options.object_mode.js

@@ -2,6 +2,35 @@ import "should";
 import { generate } from "../lib/index.js";
 
 describe("Option `objectMode`", function () {
+  for (const value of [42, "", "value"]) {
+    it(`streams ${JSON.stringify(value)} without generating all records first`, function (next) {
+      let generated = 0;
+      let generatedAtFirstRecord;
+      const records = [];
+      const generator = generate({
+        objectMode: true,
+        highWaterMark: 1,
+        length: 100,
+        columns: [
+          () => {
+            generated++;
+            return value;
+          },
+        ],
+      });
+      generator.on("data", (record) => {
+        generatedAtFirstRecord ??= generated;
+        records.push(record);
+      });
+      generator.on("error", next);
+      generator.on("end", () => {
+        generatedAtFirstRecord.should.be.within(1, 2);
+        records.should.eql(Array.from({ length: 100 }, () => [value]));
+        next();
+      });
+    });
+  }
+
   it("return an array of array", function (next) {
     this.timeout(1000000);
     generate({ seed: 1, objectMode: true, length: 4 }, (err, data) => {

packages/csv-generate/test/options.sleep.js

@@ -2,6 +2,23 @@ import "should";
 import { generate } from "../lib/index.js";
 
 describe("Option `sleep`", function () {
+  for (const value of [42, "", null, "value"]) {
+    it(`preserves all object records containing ${JSON.stringify(value)}`, async function () {
+      const data = await new Promise((resolve, reject) => {
+        generate(
+          {
+            objectMode: true,
+            length: 5,
+            sleep: 5,
+            columns: [() => value],
+          },
+          (err, data) => (err ? reject(err) : resolve(data)),
+        );
+      });
+      data.should.eql(Array.from({ length: 5 }, () => [value]));
+    });
+  }
+
   it("as integer above 0", function (next) {
     this.timeout(10000);
     generate({ duration: 1000, sleep: 100, objectMode: true }, (err, data) => {