Add spec for GitHub issue 44

https://github.com/icy-arctic-fox/spectator/issues/44

spec/issues/github_issue_44_spec.cr

@@ -0,0 +1,20 @@
+require "../spec_helper"
+
+Spectator.describe Test do
+  inject_mock Process do
+    # Instance variable that can be nil, provide a default.
+    @process_info = Crystal::System::Process.new(0)
+  end
+
+  let(command) { "ls -l" }
+  let(exception) { File::NotFoundError.new("File not found", file: "test.file") }
+
+  before_each do
+    expect(Process).to receive(:run).with(command, shell: true, output: :pipe).and_raise(exception)
+  end
+
+  skip "must stub Process.run", skip: "Method mock not applied" do
+    Process.run(command, shell: true, output: :pipe) do |process|
+    end
+  end
+end