Write test for an Angular async service method

I new to Angular and im having trouble writing unit tests for the following method for a service using jasmine/karma. Please advise?

Test needs to cover the following: this.httpClient.post was called with a url and this.httpClient.post returns data of type "ISearchResponse"

export interface ISearchTermResponse {
search_id: number;
user_id: string | null;
search_createdAt?: string;
search_term?: string;
search_isUserSearchTerm?: boolean;
}

export interface ISearchResponse {
status: string;
result: ISearchTermResponse;
}

export interface ISearchesResponse {
status: string;
response: {
searches: ISearchTermResponse[];
user_id: string | null;
};
}

async saveSearchTerm(searchTerm: string, userId: string, baseApiUrl: string) {
const saveParams = {
search_term: searchTerm,
user_id: userId ? userId : null,
};

const saveSearchUrl = baseApiUrl + env.apiEndpoints.search.paths.saveSearch;

return this.httpClient
.post<ISearchResponse>(saveSearchUrl, saveParams, {
headers: await this.headersService.getHeaders(),
})
.pipe(
timeout(env.apiEndpoints.aichat.timeout),
catchError((error) => {
console.log(
"There was an error saving search term",
error,
searchTerm,
userId
);
return throwError(() => error);
}),
finalize(() => {
//
})
);
}

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