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Add filter() and merge() methods

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This commit is contained in:
Sami Turcotte
2018-11-30 01:31:09 -05:00
parent d6660e7204
commit 46597f3185
4 changed files with 264 additions and 28 deletions
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194
src/index.spec.ts
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@@ -1,7 +1,17 @@
import test from "ava";
import { expect } from "chai";
import { Readable } from "stream";
import { fromArray, map, flatMap, split, join, collect, concat } from "./";
import {
fromArray,
map,
flatMap,
split,
join,
collect,
concat,
filter,
merge,
} from ".";
test.cb("fromArray() streams array elements in flowing mode", t => {
t.plan(3);
@@ -9,7 +19,7 @@ test.cb("fromArray() streams array elements in flowing mode", t => {
const stream = fromArray(elements);
let i = 0;
stream
.on("data", element => {
.on("data", (element: string) => {
expect(element).to.equal(elements[i]);
t.pass();
i++;
@@ -52,7 +62,7 @@ test.cb("map() maps elements synchronously", t => {
let i = 0;
source
.pipe(map((element: string) => element.toUpperCase()))
.on("data", element => {
.on("data", (element: string) => {
expect(element).to.equal(expectedElements[i]);
t.pass();
i++;
@@ -78,7 +88,7 @@ test.cb("map() maps elements asynchronously", t => {
return element.toUpperCase();
}),
)
.on("data", element => {
.on("data", (element: string) => {
expect(element).to.equal(expectedElements[i]);
t.pass();
i++;
@@ -239,6 +249,104 @@ test.cb("flatMap() emits errors during asynchronous mapping", t => {
source.push(null);
});
test.cb("filter() filters elements synchronously", t => {
t.plan(2);
const source = new Readable({ objectMode: true });
const expectedElements = ["a", "c"];
let i = 0;
source
.pipe(filter((element: string) => element !== "b"))
.on("data", (element: string) => {
expect(element).to.equal(expectedElements[i]);
t.pass();
i++;
})
.on("error", t.end)
.on("end", t.end);
source.push("a");
source.push("b");
source.push("c");
source.push(null);
});
test.cb("filter() filters elements asynchronously", t => {
t.plan(2);
const source = new Readable({ objectMode: true });
const expectedElements = ["a", "c"];
let i = 0;
source
.pipe(
filter(async (element: string) => {
await Promise.resolve();
return element !== "b";
}),
)
.on("data", (element: string) => {
expect(element).to.equal(expectedElements[i]);
t.pass();
i++;
})
.on("error", t.end)
.on("end", t.end);
source.push("a");
source.push("b");
source.push("c");
source.push(null);
});
test.cb("filter() emits errors during synchronous filtering", t => {
t.plan(2);
const source = new Readable({ objectMode: true });
source
.pipe(
filter((element: string) => {
if (element !== "a") {
throw new Error("Failed filtering");
}
return true;
}),
)
.resume()
.on("error", err => {
expect(err.message).to.equal("Failed filtering");
t.pass();
})
.on("end", t.end);
source.push("a");
source.push("b");
source.push("c");
source.push(null);
});
test.cb("filter() emits errors during asynchronous filtering", t => {
t.plan(2);
const source = new Readable({ objectMode: true });
source
.pipe(
filter(async (element: string) => {
await Promise.resolve();
if (element !== "a") {
throw new Error("Failed filtering");
}
return true;
}),
)
.resume()
.on("error", err => {
expect(err.message).to.equal("Failed filtering");
t.pass();
})
.on("end", t.end);
source.push("a");
source.push("b");
source.push("c");
source.push(null);
});
test.cb("split() splits chunks using the default separator (\\n)", t => {
t.plan(5);
const source = new Readable({ objectMode: true });
@@ -445,7 +553,7 @@ test.cb(
const expectedElements = ["a", "b", "c", "d", "e", "f"];
let i = 0;
concat(source1, source2)
.on("data", element => {
.on("data", (element: string) => {
expect(element).to.equal(expectedElements[i]);
t.pass();
i++;
@@ -505,7 +613,7 @@ test.cb(
const expectedElements = ["a", "b", "c", "d", "e", "f"];
let i = 0;
concat(source1, source2)
.on("data", element => {
.on("data", (element: string) => {
expect(element).to.deep.equal(Buffer.from(expectedElements[i]));
t.pass();
i++;
@@ -548,13 +656,13 @@ test.cb(
.on("end", t.end);
source1.push("a");
source2.push("d");
source1.push("b");
source2.push("e");
source1.push("c");
source2.push("f");
source2.push(null);
source1.push(null);
setTimeout(() => source2.push("d"), 10);
setTimeout(() => source1.push("b"), 20);
setTimeout(() => source2.push("e"), 30);
setTimeout(() => source1.push("c"), 40);
setTimeout(() => source2.push("f"), 50);
setTimeout(() => source2.push(null), 60);
setTimeout(() => source1.push(null), 70);
},
);
@@ -564,7 +672,7 @@ test.cb("concat() concatenates a single readable stream (object mode)", t => {
const expectedElements = ["a", "b", "c", "d", "e", "f"];
let i = 0;
concat(source)
.on("data", element => {
.on("data", (element: string) => {
expect(element).to.equal(expectedElements[i]);
t.pass();
i++;
@@ -586,7 +694,7 @@ test.cb(
const expectedElements = ["a", "b", "c", "d", "e", "f"];
let i = 0;
concat(source)
.on("data", element => {
.on("data", (element: string) => {
expect(element).to.deep.equal(Buffer.from(expectedElements[i]));
t.pass();
i++;
@@ -611,3 +719,59 @@ test.cb("concat() concatenates empty list of readable streams", t => {
.on("error", t.end)
.on("end", t.end);
});
test.cb.only(
"merge() merges multiple readable streams in chunk arrival order",
t => {
t.plan(6);
const source1 = new Readable({ objectMode: true, read: () => ({}) });
const source2 = new Readable({ objectMode: true, read: () => ({}) });
const expectedElements = ["a", "d", "b", "e", "c", "f"];
let i = 0;
merge(source1, source2)
.on("data", (element: string) => {
expect(element).to.equal(expectedElements[i]);
t.pass();
i++;
})
.on("error", t.end)
.on("end", t.end);
source1.push("a");
setTimeout(() => source2.push("d"), 10);
setTimeout(() => source1.push("b"), 20);
setTimeout(() => source2.push("e"), 30);
setTimeout(() => source1.push("c"), 40);
setTimeout(() => source2.push("f"), 50);
setTimeout(() => source2.push(null), 60);
setTimeout(() => source1.push(null), 70);
},
);
test.cb("merge() merges a readable stream", t => {
t.plan(3);
const source = new Readable({ objectMode: true, read: () => ({}) });
const expectedElements = ["a", "b", "c"];
let i = 0;
merge(source)
.on("data", (element: string) => {
expect(element).to.equal(expectedElements[i]);
t.pass();
i++;
})
.on("error", t.end)
.on("end", t.end);
source.push("a");
source.push("b");
source.push("c");
source.push(null);
});
test.cb("merge() merges an empty list of readable streams", t => {
t.plan(0);
merge()
.on("data", () => t.pass())
.on("error", t.end)
.on("end", t.end);
});