test: Add unit tests for DNS dispatcher logic #4
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Introduces comprehensive unit tests for the `DNSDispatcher` to verify core functionality like blocking, caching, and upstream resolution. * Tests successful lookups. * Verifies NXDOMAIN responses for blocked domains. * Checks cache hit and miss behavior. The `github.com/stretchr/testify` dependency was added to enable mocking DNS responses and provide robust assertions.
Summary of ChangesHello @rm-hull, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed! This pull request significantly improves the test coverage for the Highlights
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Code Review
This pull request introduces valuable unit tests for the DNSDispatcher, covering core functionality like allowed/blocked domains and caching. The tests are well-structured, but I've identified a critical issue in TestDNSDispatcher_HandleDNSRequest_MultipleQuestions. The test's assertions are incorrect for the current implementation and, more importantly, they highlight a significant flaw in how the dispatcher handles requests with multiple questions. I've provided a fix for the test and strongly recommend addressing the underlying bug in the production code. I've also included a couple of medium-severity suggestions to improve test maintainability and isolation.
| var blockList = NewBlockList([]string{"ads.0xbt.net"}, 0.0001) | ||
| var upstream = "8.8.8.8:53" |
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Using global variables for test setup can introduce side effects between tests, especially if tests are run in parallel in the future (t.Parallel()). It's a best practice to define these variables within each test function or a test-specific setup function to ensure complete test isolation.
| func TestDNSDispatcher_HandleDNSRequest_Allowed(t *testing.T) { | ||
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| dispatcher := NewDNSDispatcher(upstream, blockList, 100) | ||
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| req := new(dns.Msg) | ||
| req.SetQuestion("google.com.", dns.TypeA) | ||
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| writer := new(MockResponseWriter) | ||
| writer.On("WriteMsg", mock.Anything).Return(nil) | ||
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| // Call the method under test | ||
| dispatcher.HandleDNSRequest(writer, req) | ||
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| // Assert that the response writer was called with a non-nil message | ||
| assert.NotNil(t, writer.WrittenMsg) | ||
| assert.Equal(t, dns.RcodeSuccess, writer.WrittenMsg.Rcode) | ||
| } | ||
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| func TestDNSDispatcher_HandleDNSRequest_Blocked(t *testing.T) { | ||
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| dispatcher := NewDNSDispatcher(upstream, blockList, 100) | ||
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| req := new(dns.Msg) | ||
| req.SetQuestion("ads.0xbt.net.", dns.TypeA) | ||
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| writer := new(MockResponseWriter) | ||
| writer.On("WriteMsg", mock.Anything).Return(nil) | ||
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| // Call the method under test | ||
| dispatcher.HandleDNSRequest(writer, req) | ||
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| // Assert that the response has an NXDOMAIN Rcode | ||
| assert.NotNil(t, writer.WrittenMsg) | ||
| assert.Equal(t, dns.RcodeNameError, writer.WrittenMsg.Rcode) | ||
| } |
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The tests TestDNSDispatcher_HandleDNSRequest_Allowed and TestDNSDispatcher_HandleDNSRequest_Blocked share a lot of boilerplate code. To improve maintainability and reduce duplication, consider refactoring them into a single table-driven test. This would make it easier to add more test cases in the future.
The `NewDNSDispatcher` function is updated to return an error, propagating registration failures for Prometheus collectors. A new helper function `shouldRegister` handles collector registration, ignoring `AlreadyRegisteredError` but returning other errors. This change ensures that dispatcher creation fails if essential metrics cannot be properly initialized in `internal/dns.go`. Corresponding error handling is added in `internal/app.go` and tests in `internal/dns_test.go` are updated.
This file standardizes formatting rules across the repository.
Key settings include:
* Enforcing spaces for most files (4 spaces for Python,
2 for YAML/JSON).
* Standardizing `lf` line endings and `utf-8` charset.
* Setting specific line length limits for Python code (120)
and docstrings (72).
* Requiring tabs for `Makefile` and **.go** files.
Set up continuous integration using GitHub Actions. The workflow handles: * Building, testing (Go 1.25), linting, and coverage reporting. * Building and pushing the Docker image to GHCR on `main` or tags. Also configure Dependabot to manage dependencies for Go modules, GitHub Actions, and Docker base images.
Align expectations in the multiple questions DNS test with the current implementation bug. If a DNS request contains multiple questions and one query is blocked, the system currently returns `NXDOMAIN` instead of handling the valid queries. This test is updated to reflect that temporary faulty behavior. The true fix is tracked elsewhere.
Pull Request Test Coverage Report for Build 19086843140Details
💛 - Coveralls |
Introduces comprehensive unit tests for the
DNSDispatcherto verify core functionality like blocking, caching, and upstream resolution.The
github.com/stretchr/testifydependency was added to enable mocking DNS responses and provide robust assertions.