public async Task CopyFileToRunningContainer() { // Given const string dayOfWeekFilePath = "/tmp/dayOfWeek"; var dayOfWeek = DateTime.UtcNow.DayOfWeek.ToString(); var testcontainersBuilder = new TestcontainersBuilder <TestcontainersContainer>() .WithImage("alpine") .WithEntrypoint(KeepTestcontainersUpAndRunning.Command); // When // Then await using (ITestcontainersContainer testcontainer = testcontainersBuilder.Build()) { await testcontainer.StartAsync(); await testcontainer.CopyFileAsync(dayOfWeekFilePath, Encoding.Default.GetBytes(dayOfWeek)); Assert.Equal(0, (await testcontainer.ExecAsync(new[] { "/bin/sh", "-c", $"test \"$(cat {dayOfWeekFilePath})\" = \"{dayOfWeek}\"" })).ExitCode); Assert.Equal(0, (await testcontainer.ExecAsync(new[] { "/bin/sh", "-c", $"stat {dayOfWeekFilePath} | grep 0600" })).ExitCode); } }