Consider Supporting test command JSON messages

[bflad]

Description

Running the upcoming terraform test -json command has specific JSON message types, e.g.

{"@level":"info","@message":"Found 1 file and 1 run block","@module":"terraform.ui","@timestamp":"2023-07-25T10:03:42.974507-04:00","test_abstract":{"tests/passthrough.tftest":["variable_output_passthrough"]},"type":"test_abstract"}
{"@level":"info","@message":"tests/passthrough.tftest... fail","@module":"terraform.ui","@testfile":"tests/passthrough.tftest","@timestamp":"2023-07-25T10:03:42.977420-04:00","test_file":{"path":"tests/passthrough.tftest","status":"fail"},"type":"test_file"}
{"@level":"info","@message":"  \"variable_output_passthrough\"... fail","@module":"terraform.ui","@testfile":"tests/passthrough.tftest","@testrun":"variable_output_passthrough","@timestamp":"2023-07-25T10:03:42.977444-04:00","test_run":{"path":"tests/passthrough.tftest","run":"variable_output_passthrough","status":"fail"},"type":"test_run"}
{"@level":"error","@message":"Error: Test assertion failed","@module":"terraform.ui","@testfile":"tests/passthrough.tftest","@testrun":"variable_output_passthrough","@timestamp":"2023-07-25T10:03:42.977566-04:00","diagnostic":{"severity":"error","summary":"Test assertion failed","detail":"variable was not passed through to output","range":{"filename":"tests/passthrough.tftest","start":{"line":9,"column":21,"byte":123},"end":{"line":9,"column":50,"byte":152}},"snippet":{"context":"run \"variable_output_passthrough\"","code":"    condition     = output.test == \"test value 2\"","start_line":9,"highlight_start_offset":20,"highlight_end_offset":49,"values":[{"traversal":"output.test","statement":"is \"test value\""}]}},"type":"diagnostic"}
{"@level":"info","@message":"Failure! 0 passed, 1 failed.","@module":"terraform.ui","@timestamp":"2023-07-25T10:03:42.980799-04:00","test_summary":{"status":"fail","passed":0,"failed":1,"errored":0,"skipped":0},"type":"test_summary"}

Proposal

Add the following type definitions, similar to Diagnostic message handling:

// "test_abstract":{"tests/passthrough.tftest":["variable_output_passthrough"]}
// Could potentially be defined as type TestAbstract map[string][]string

// "test_file":{"path":"tests/passthrough.tftest","status":"fail"}
type TestFile struct {
  Path string
  Status string // potentially introduce constants?
}

// "test_run":{"path":"tests/passthrough.tftest","run":"variable_output_passthrough","status":"fail"}
type TestRun struct {
  Path string
  Run string
  Status string // potentially introduce constants?
}

// "test_summary":{"status":"fail","passed":0,"failed":1,"errored":0,"skipped":0}
type TestSummary struct {
  Errored int
  Failed int
  Passed int
  Skipped int
  Status string // potentially introduce constants?
}