Simplify external API of diffing

Also pass teams and repos to `create_diff` explicitly, which will allow easier mocking.

src/github/mod.rs

@@ -1,7 +1,7 @@
 mod api;
 
 use self::api::{BranchProtectionOp, TeamPrivacy, TeamRole};
-use crate::{github::api::RepoPermission, TeamApi};
+use crate::github::api::RepoPermission;
 use log::debug;
 use rust_team_data::v1::Bot;
 use std::collections::{HashMap, HashSet};
@@ -12,7 +12,16 @@ pub(crate) use self::api::{GitHubRead, GitHubWrite};
 static DEFAULT_DESCRIPTION: &str = "Managed by the rust-lang/team repository.";
 static DEFAULT_PRIVACY: TeamPrivacy = TeamPrivacy::Closed;
 
-pub(crate) struct SyncGitHub {
+pub(crate) fn create_diff(
+    github: GitHubRead,
+    teams: Vec<rust_team_data::v1::Team>,
+    repos: Vec<rust_team_data::v1::Repo>,
+) -> anyhow::Result<Diff> {
+    let github = SyncGitHub::new(github, teams, repos)?;
+    github.diff_all()
+}
+
+struct SyncGitHub {
     github: GitHubRead,
     teams: Vec<rust_team_data::v1::Team>,
     repos: Vec<rust_team_data::v1::Repo>,
@@ -21,10 +30,11 @@ pub(crate) struct SyncGitHub {
 }
 
 impl SyncGitHub {
-    pub(crate) fn new(github: GitHubRead, team_api: &TeamApi) -> anyhow::Result<Self> {
-        let teams = team_api.get_teams()?;
-        let repos = team_api.get_repos()?;
-
+    pub(crate) fn new(
+        github: GitHubRead,
+        teams: Vec<rust_team_data::v1::Team>,
+        repos: Vec<rust_team_data::v1::Repo>,
+    ) -> anyhow::Result<Self> {
         debug!("caching mapping between user ids and usernames");
         let users = teams
             .iter()

src/main.rs

@@ -4,7 +4,7 @@ mod team_api;
 mod utils;
 mod zulip;
 
-use crate::github::{GitHubRead, GitHubWrite, SyncGitHub};
+use crate::github::{create_diff, GitHubRead, GitHubWrite};
 use crate::team_api::TeamApi;
 use anyhow::Context;
 use log::{error, info, warn};
@@ -82,8 +82,9 @@ fn app() -> anyhow::Result<()> {
             "github" => {
                 let token = get_env("GITHUB_TOKEN")?;
                 let gh_read = GitHubRead::new(token.clone())?;
-                let sync = SyncGitHub::new(gh_read, &team_api)?;
-                let diff = sync.diff_all()?;
+                let teams = team_api.get_teams()?;
+                let repos = team_api.get_repos()?;
+                let diff = create_diff(gh_read, teams, repos)?;
                 info!("{}", diff);
                 if !only_print_plan {
                     let gh_write = GitHubWrite::new(token, dry_run)?;