import * as fs from "fs"

const defaultdict = <K>(defaultValue: number) => {
    const dict: Map<K, number> = new Map()

    const get = (key: K): number => {
        return dict.has(key) ? dict.get(key) : defaultValue
    }

    const set = (key: K, value: number): void => {
        dict.set(key, value)
    }

    const add = (key: K, value: number): void => {
        dict.has(key) ? set(key, get(key) + value) : set(key, value)
    }

    const del = (key: K): boolean => {
        return dict.delete(key)
    }

    return { get, add, set, del }
}


const range = (start: number) => (stop: number) => {
    return Array.from(Array(stop - start), (_, k) => k + start)
}

const existsSameValue = <T>(arr: T[]): boolean => {
    const g: Set<T> = new Set(arr)
    return g.size !== arr.length
}

const main = (args: string): void => {
    const input = args.trim().split("\n");
    const T = parseInt(input.shift())
    for (let i = 0; i < T; i++) {
        const [N, M] = input.shift().split(" ").map(x => Number(x))
        const G = defaultdict(0)
        for (let j = 0; j < M; j++) {
            const [u, v] = input.shift().split(" ").map(x => Number(x))
            G.add(u, 1)
            G.add(v, 1)
        }
        const degree = range(1)(N + 1).map(x => G.get(x))
        console.log(existsSameValue(degree) ? "Yes" : "No")
    }

}

main(fs.readFileSync('/dev/stdin', 'utf8'));