Demo App: outerspace-go

This is a demo app that uses the SpaceX API to fetch data about SpaceX launches, rockets, and capsules. It also talks to a numbers API that consistently generates random results.

Working Locally

How to run the go app locally

This will run a server on port :8080 with the API endpoints.

go run main.go

How to run the tests locally

There is a test file under lib/api_testify_test.go that loops through a set of API calls that were recorded using proxymock and replays each one. It then compares the response of each one to what was previously recorded. You can run it like so:

go test -v ./...

How to build the go binary locally

This will build the app and create the binary.

go build

Working with proxymock

For apps that make lots of API calls, proxymock can be used to capture and replay those downstream calls.

Capture with proxymock

All you have to do is set the following environment variables before you run the go code:

export http_proxy=http://localhost:4140
export https_proxy=http://localhost:4140
go run main.go

Then in another window run proxymock run which will start to capture data:

proxymock run

For examples of the kind of data collected, check the .speedscale directory of the repository.

Running tests with proxymock

You may find that because the Numbers API returns random values that the test usually fails. The solution for this is to run proxymock first and then run the tests. First import the existing data into proxymock, and take note of the snapshot id that is created.

proxymock import --file .speedscale/raw.jsonl

If you want to see what the data looks like, you can use the inspect command:

proxymock inspect snapshot "$SNAPSHOT_ID"

API List

You can see a list of every API call that was recorded, both inbound to your application and outbound to downstream systems.

Drill-down

Using your arrow keys you can navigate to a particular call and see all the details of what request was sent and how the application responded. Here we can see the exact value returned from the Numbers API.

Once you are ready to use that data you can then run with that snapshot:

proxymock run --snapshot-id "$SNAPSHOT_ID"

Now in your window where you are going to run the tests, make sure to export the environment variables and run the test again:

export http_proxy=http://localhost:4140
export https_proxy=http://localhost:4140
go test -v ./...

You should see that all the tests are now passing because proxymock is mocking out the Numbers API with a consistent and repeatable result.