Add Dotenv.parse method

[rossta]

Opening the PR for discussion around a new feature request.

Exposes parsing logic as a public API to allow programmatic inspection of .env files without modifying ENV.

One such use case is for automated application setup to create/read/modify .env files prior to running the application for the first time. I found the need to dive into Dotenv internals to accomplish such a task while debugging installation scripts on a recent project and thought it would be useful to avoid relying on internal details.

[jonmagic]

I might find this useful. Would you mind adding docs to the README and I'll get it shipped?

[rossta]

@jonmagic Thanks, updated to document in README.

[jonmagic]

Only one suggestion. Let me know what you think and I'll get it shipped.

[c9s]

Hi folks,

we have an use case like this:

dotenv -f .env.test bundle exec rspec --pattern "./spec/models/**/*.rb"

this use case is broken right after the dotenv 2.7.0 release. The --pattern option is consumed by dotenv and therefore it raises an "Unknown option" error. I guess this is related to this PR.

[cadwallion]

👋 I believe it might actually related to #374 where I implemented an actual options parser. Sorry for the inconvenience this has caused!

I'll take a look at this now.

[cadwallion]

👋 @c9s I believe you can get the same net effect with the following:

dotenv -f .env.test "bundle exec rspec --pattern './spec/models/**/*.rb'"

The options parser is reading your subsequent script as part of dotenv invocation instead of the command you wish to invoke. I can take a look at alternatives in a separate PR for a future patch, but this should resolve your issue immediately.