trace+tester: Adding local var values to trace and test report

[johanfylling]

Local variable values in test report

When enabled (--var-values flag), the failure report for tests will contain values for variables local to the failing expression. e.g.:

FAILURES
--------------------------------------------------------------------------------
data.test.test_foo: FAIL (0ms)

  test.rego:8:
        x == y + z
        |    |   |
        |    |   3
        |    y + z: 5
        |    y: 2
        1

SUMMARY
--------------------------------------------------------------------------------
test.rego:
data.test.test_foo: FAIL (0ms)
--------------------------------------------------------------------------------
FAIL: 1/1

Local variable values in pretty trace

When enabled on eval and test commands (--var-values flag), local variable values are added to pretty trace:

query:1          Enter data.test.p = _                                {}
query:1          | Eval data.test.p = _                               {}
query:1          | Index data.test.p (matched 1 rule, early exit)     {}
/test.rego:4     | Enter data.test.p                                  {}
/test.rego:5     | | Eval x = 1                                       {}
/test.rego:6     | | Eval y = 2                                       {}
/test.rego:7     | | Eval z = 3                                       {}
/test.rego:8     | | Eval minus(z, y, __local3__)                     {y: 2, z: 3}
/test.rego:8     | | Eval x = __local3__                              {__local3__: 1, x: 1}
/test.rego:4     | | Exit data.test.p early                           {}
query:1          | Exit data.test.p = _                               {_: true, data.test.p: true}
query:1          Redo data.test.p = _                                 {_: true, data.test.p: true}
query:1          | Redo data.test.p = _                               {_: true, data.test.p: true}
/test.rego:4     | Redo data.test.p                                   {}
/test.rego:8     | | Redo x = __local3__                              {__local3__: 1, x: 1}
/test.rego:8     | | Redo minus(z, y, __local3__)                     {__local3__: 1, y: 2, z: 3}
/test.rego:7     | | Redo z = 3                                       {z: 3}
/test.rego:6     | | Redo y = 2                                       {y: 2}
/test.rego:5     | | Redo x = 1                                       {x: 1}

Fixing: #2546

[netlify[bot]]

✅ Deploy Preview for openpolicyagent ready!

Name	Link
🔨 Latest commit	4ea05387f229fa593310fc9b82640d9b128cfba4
🔍 Latest deploy log	https://app.netlify.com/sites/openpolicyagent/deploys/667a99d0d1b8ff000899632e
😎 Deploy Preview	https://deploy-preview-6815--openpolicyagent.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[johanfylling]

The linter fails because it gets confused by some newer golang stuff: https://github.com/open-policy-agent/opa/pull/6817