Add the WrappedError class

lib/telebugs/wrapped_error.rb

@@ -0,0 +1,22 @@
+module Telebugs
+  # WrappedError unwraps an error and its causes up to a certain depth.
+  class WrappedError
+    MAX_NESTED_ERRORS = 3
+
+    def initialize(error)
+      @error = error
+    end
+
+    def unwrap
+      error_list = []
+      error = @error
+
+      while error && error_list.size < MAX_NESTED_ERRORS
+        error_list << error
+        error = error.cause
+      end
+
+      error_list
+    end
+  end
+end

test/test_wrapped_error.rb

@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+class TestWrappedError < Minitest::Test
+  def test_unwraps_errors_without_a_cause
+    error = StandardError.new
+    wrapped = Telebugs::WrappedError.new(error)
+
+    assert_equal [error], wrapped.unwrap
+  end
+
+  def test_unwraps_no_more_than_3_nested_errors
+    begin
+      raise RuntimeError, "error 1"
+    rescue => e1
+      begin
+        raise RuntimeError, "error 2"
+      rescue => e2
+        begin
+          raise RuntimeError, "error 3"
+        rescue => e3
+          begin
+            raise RuntimeError, "error 4"
+          rescue => e4
+            begin
+              raise RuntimeError, "error 5"
+            rescue => e5
+            end
+          end
+        end
+      end
+    end
+
+    wrapped = Telebugs::WrappedError.new(e5)
+    unwrapped = wrapped.unwrap
+
+    assert_equal 3, unwrapped.size
+    assert_equal [e5, e4, e3], unwrapped
+  end
+end