fix: retry docker volume remove (!399)

Closes coop-cloud/organising#509

Reviewed-on: coop-cloud/abra#399
Reviewed-by: decentral1se <decentral1se@noreply.git.coopcloud.tech>
Co-authored-by: p4u1 <p4u1_f4u1@riseup.net>
Co-committed-by: p4u1 <p4u1_f4u1@riseup.net>

cli/app/remove_test.go

@@ -0,0 +1,26 @@
+package app
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestRetryFunc(t *testing.T) {
+	err := retryFunc(1, func() error { return nil })
+	if err != nil {
+		t.Errorf("should not return an error: %s", err)
+	}
+
+	i := 0
+	fn := func() error {
+		i++
+		return fmt.Errorf("oh no, something went wrong!")
+	}
+	err = retryFunc(2, fn)
+	if err == nil {
+		t.Error("should return an error")
+	}
+	if i != 2 {
+		t.Errorf("The function should have been called 1 times, got %d", i)
+	}
+}