Add offline mode

[RossComputerGuy]

• Adds an --offline flag which is useful for sandbox/networkless build systems such as Nix.

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[bkonyi]

Sorry for the delay on this @RossComputerGuy! Overall, this change looks good to me, but we should add some tests before landing.

[RossComputerGuy]

I've gone ahead and rebased it. I will look into getting tests in shortly.

[RossComputerGuy]

Can't figure out how the test should be done, I see there's configuration tests but none invoke read.

[bkonyi]

Can't figure out how the test should be done, I see there's configuration tests but none invoke read.

I think you can either add a test like this or something similar to what's done in this file.

Basically, you'll just want a test that runs webdev serve --no-pub on a project that hasn't had dart pub get invoked to pull down the dependencies. The webdev serve --no-pub should fail to serve the project since there will be unresolved dependencies.

[RossComputerGuy]

Ok, I added the test.

[bkonyi]

I'm not really sure what's going on with these lines. Could we not get the package directory simply by doing p.dirname(p.dirname(Platform.script.toFilePath())?

[RossComputerGuy]

That gives me /tmp

[bkonyi]

Ah right, because the test runner generates an entrypoint...

In that case, I think we should continue to activate webdev from pub instead of using --source path. This test should still work as long as we don't run dart pub get on the created project before running webdev serve --offline.

[RossComputerGuy]

Oh ok, I was assuming we would do it the way I did so new updates would actually work. I was getting an error saying --offline wasn't a recognized flag even if I did activate it outside the test.

[bkonyi]

Right, that's a great point. Given that, I think we should move the test to webdev/test/integration_test.dart. The tests there run webdev from source so we won't have to worry about publishing before this new test will pass.