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decoder.test.ts
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260 lines (221 loc) · 7.86 KB
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import { describe, expect, it } from "vitest"
// eslint-disable-next-line antfu/no-import-dist
import { Decoder } from "../dist/decoder.mjs"
describe(".currentOffset", () => {
it("example works as described", () => {
const buffer = new Uint8Array([0x01, 0x01, 0x00, 0x00])
const decoder = new Decoder(buffer)
expect(decoder.readUint32()).toBe(257)
expect(decoder.currentOffset).toBe(4)
})
})
describe(".endianness", () => {
it("example works as described", () => {
const buffer = new Uint8Array([0x00, 0x00, 0x01, 0x01])
const decoder = new Decoder(buffer)
decoder.endianness("big")
expect(decoder.readUint32()).toBe(257)
})
})
describe(".seek", () => {
it("example works as described", () => {
const buffer = new Uint8Array([0xff, 0xff, 0x01, 0x00])
const decoder = new Decoder(buffer)
expect(decoder.seek(2)).toBe(0)
expect(decoder.readUint16()).toBe(1)
})
})
describe(".goto", () => {
it("example works as described", () => {
const buffer = new Uint8Array([0xff, 0xff, 0x01, 0x00])
const decoder = new Decoder(buffer)
expect(decoder.readUint16()).toBe(65535)
expect(decoder.goto(0)).toBe(2)
expect(decoder.currentOffset).toBe(0)
expect(decoder.readUint16()).toBe(65535)
})
})
describe(".alignTo", () => {
it("skips forwards correctly if diff if positive", () => {
const decoder = new Decoder(new Uint8Array(16))
decoder.seek(12)
decoder.alignTo(16)
expect(decoder.currentOffset).toBe(16)
})
it("skips forwards correctly if diff if negative", () => {
const decoder = new Decoder(new Uint8Array(16))
decoder.seek(4)
decoder.alignTo(16)
expect(decoder.currentOffset).toBe(16)
})
it("does nothing if already aligned", () => {
const decoder = new Decoder(new Uint8Array(16))
decoder.seek(8)
decoder.alignTo(4)
expect(decoder.currentOffset).toBe(8)
})
it("example works as described", () => {
// prettier-ignore
// Assume we have a header 5 bytes long, then 3 bytes of padding up to 8 bytes in, then more data
const buffer = new Uint8Array([
0x74, 0xee, 0xb2, 0x36, 0x0c, 0x00, 0x00, 0x00,
0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
])
const decoder = new Decoder(buffer)
// First we move the offset past the header
expect(decoder.seek(5)).toBe(0)
// Then we can align to the next 8 byte boundary
decoder.alignTo(8)
expect(decoder.currentOffset).toBe(8)
expect(decoder.readUint64()).toBe(1n)
})
})
describe("integers", () => {
describe(".readInt8", () => {
it("example works as described", () => {
const decoder = new Decoder(new Uint8Array([0xff]))
expect(decoder.readInt8()).toBe(-1)
})
it("pointer example works as described", () => {
// (3 + 0) | pad | -1
const decoder = new Decoder(new Uint8Array([0x03, 0x00, 0x00, 0xff]))
const pointer = decoder.readUint16()
expect(pointer).toBe(3)
expect(decoder.readInt8({ pointer })).toBe(-1)
})
})
describe(".readUint8", () => {
it("example works as described", () => {
const decoder = new Decoder(new Uint8Array([0xff]))
expect(decoder.readUint8()).toBe(255)
})
it("pointer example works as described", () => {
// (3 + 0) | pad | -1
const decoder = new Decoder(new Uint8Array([0x03, 0x00, 0x00, 0xff]))
const pointer = decoder.readUint16()
expect(pointer).toBe(3)
expect(decoder.readUint8({ pointer })).toBe(255)
})
})
describe(".readInt16", () => {
it("example works as described", () => {
const decoder = new Decoder(new Uint8Array([0xff, 0xff]))
expect(decoder.readInt16()).toBe(-1)
})
it("pointer example works as described", () => {
const decoder = new Decoder(new Uint8Array([0x03, 0x00, 0x00, 0xff, 0xff]))
const pointer = decoder.readUint16()
expect(pointer).toBe(3)
expect(decoder.readInt16({ pointer })).toBe(-1)
})
})
describe(".readUint16", () => {
it("decodes a value correctly", () => {
const decoder = new Decoder(new Uint8Array([0xff, 0xff]))
expect(decoder.readUint16()).toBe(65535)
})
it("decodes a value via a pointer correctly", () => {
// (3 + 0) | pad | -1
const decoder = new Decoder(new Uint8Array([0x03, 0x00, 0x00, 0xff, 0xff]))
const pointer = decoder.readUint16()
expect(pointer).toBe(3)
expect(decoder.readUint16({ pointer })).toBe(65535)
})
})
})
describe(".readBuffer", () => {
it("returns part of buffer", () => {
const decoder = new Decoder(
new Uint8Array([0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08]),
)
expect(decoder.readBuffer({ length: 2 })).toEqual(new Uint8Array([0x01, 0x02]))
})
it("uses currentOffset", () => {
const decoder = new Decoder(
new Uint8Array([0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08]),
)
decoder.seek(2)
expect(decoder.readBuffer({ length: 2 })).toEqual(new Uint8Array([0x03, 0x04]))
})
it("pointer option works", () => {
const decoder = new Decoder(
new Uint8Array([0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x08, 0x09]),
)
expect(decoder.readBuffer({ pointer: 0x06, length: 2 })).toEqual(
new Uint8Array([0x08, 0x09]),
)
})
})
describe(".readString", () => {
it("should parse strings correctly", () => {
const data = new TextEncoder().encode("testhelloworld")
const decoder = new Decoder(data)
expect(decoder.readString({ length: 4 })).toBe("test")
expect(decoder.readString({ length: 5 })).toBe("hello")
expect(decoder.readString({ length: 5 })).toBe("world")
})
it("should parse zeroed strings correctly", () => {
const data = new TextEncoder().encode("test\x00hello\x00world\x00")
const decoder = new Decoder(data)
expect(decoder.readString({ zeroed: true })).toBe("test")
expect(decoder.readString({ zeroed: true })).toBe("hello")
expect(decoder.readString({ zeroed: true })).toBe("world")
})
})
it("should parse the README example", () => {
const data = new Uint8Array([
0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x2c, 0x20, 0x57, 0x6f, 0x72, 0x6c, 0x64, 0x21,
])
const decoder = new Decoder(data)
// You can use it to just read data straight from the buffer
expect(decoder.readString({ length: 5 })).toBe("Hello")
expect(decoder.readString({ length: 7 })).toBe(", World")
// Or you can use it more ergonomically when possible
const filledArray = new Uint8Array(2)
filledArray.fill(2)
const decoder2 = new Decoder(filledArray)
const result = {
a: decoder2.readUint8(),
b: decoder2.readUint8(),
}
expect(result).toEqual({ a: 2, b: 2 })
})
it("should allow parsing simple data", () => {
const testBuffer = new Uint8Array(17)
const values = [3257, 3263, 6483, 9773]
const view = new DataView(testBuffer.buffer)
view.setInt8(0, 4)
view.setInt8(1, 5)
view.setInt8(5, 11)
view.setInt16(11, values[0], true)
view.setInt8(2, 6)
view.setInt8(6, 9)
view.setInt16(9, values[1], true)
view.setInt8(3, 7)
view.setInt8(7, 15)
view.setInt16(15, values[2], true)
view.setInt8(4, 8)
view.setInt8(8, 13)
view.setInt16(13, values[3], true)
const parser = new Decoder(testBuffer)
const entryCount = parser.readUint8()
expect(entryCount).toBe(4)
const entryOffsets = []
for (let i = 0; i < entryCount; i++) {
const entryOffset = parser.readUint8()
entryOffsets.push(entryOffset)
expect(entryOffset).toBe(5 + i)
}
const valueOffsets = []
for (let i = 0; i < entryCount; i++) {
const valueOffset = parser.readUint8({ pointer: entryOffsets[i] })
valueOffsets.push(valueOffset)
}
parser.seek(4)
for (let i = 0; i < entryCount; i++) {
const value = parser.readUint16({ pointer: valueOffsets[i] })
expect(value).toBe(values[i])
}
parser.seek(8)
expect(parser.currentOffset).toBe(17)
})