Adding accounts lookup API endpoint

accounts.go

@@ -70,6 +70,17 @@ func (c *Client) GetAccountCurrentUser(ctx context.Context) (*Account, error) {
 	return &account, nil
 }
 
+func (c *Client) AccountLookup(ctx context.Context, acct string) (*Account, error) {
+	var account Account
+	params := url.Values{}
+	params.Set("acct", acct)
+	err := c.doAPI(ctx, http.MethodGet, "/api/v1/accounts/lookup", params, &account, nil)
+	if err != nil {
+		return nil, err
+	}
+	return &account, nil
+}
+
 // Profile is a struct for updating profiles.
 type Profile struct {
 	// If it is nil it will not be updated.

accounts_test.go

@@ -38,6 +38,40 @@ func TestGetAccount(t *testing.T) {
 	}
 }
 
+func TestAccountLookup(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/api/v1/accounts/lookup" {
+			http.Error(w, http.StatusText(http.StatusNotFound), http.StatusNotFound)
+			return
+		}
+		acct := r.URL.Query().Get("acct")
+		if acct != "foo@bar" {
+			http.Error(w, http.StatusText(http.StatusNotFound), http.StatusNotFound)
+			return
+		}
+		fmt.Fprintln(w, `{"username": "foo@bar"}`)
+	}))
+	defer ts.Close()
+
+	client := NewClient(&Config{
+		Server:       ts.URL,
+		ClientID:     "foo",
+		ClientSecret: "bar",
+		AccessToken:  "zoo",
+	})
+	_, err := client.AccountLookup(context.Background(), "123")
+	if err == nil {
+		t.Fatalf("should be fail: %v", err)
+	}
+	a, err := client.AccountLookup(context.Background(), "foo@bar")
+	if err != nil {
+		t.Fatalf("should not be fail: %v", err)
+	}
+	if a.Username != "foo@bar" {
+		t.Fatalf("want %q but %q", "foo@bar", a.Username)
+	}
+}
+
 func TestGetAccountCurrentUser(t *testing.T) {
 	canErr := true
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {