Throughout the COVID-19 pandemic, communities of color have faced significantly higher rates of COVID-19 infection, as well as poor clinical outcomes. These differences are driven by long-standing structural inequities that prevent effective social distancing efforts and are further exacerbated by disparities in COVID-19 testing. Our study applied the concept of "COVID-19 testing deserts" to systematically identify gaps in testing resource allocation across Massachusetts in May 2020 and March 2021. Testing deserts were identified at the census tract level, using criteria developed by the Department of Agriculture for food deserts. Testing deserts occurred more frequently in segregated Hispanic, segregated Black, mixed minority, and integrated communities, as well as in neighborhoods with low vehicle access and in federally designated Medically Underserved Areas. Segregated communities were those in which more than 50 percent of the population self-identified as non-Hispanic White, Hispanic, non-Hispanic Black, or non-Hispanic Asian, respectively. Testing deserts were overrepresented in counties with high COVID-19 incidence rates, suggesting that testing accessibility is essential for prompt COVID-19 diagnosis and self-isolation.