fix(router): call BuildRouterChain method when creating directory.

[yangpixi]

Description

Fixes #3222

Call BuildRouterChain method when creating static directory to ensure router capabilities work properly.
Currently, dubbo-go does not support static router configuration, with the exception of the Tag Router. (Pending #3219 to support this).

Checklist

• I confirm the target branch is develop
• Code has passed local testing
• I have added tests that prove my fix is effective or that my feature works

[sonarqubecloud]

Quality Gate passed

Issues
10 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov-commenter]

Codecov Report

❌ Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 47.91%. Comparing base (35ea886) to head (664bce8).
⚠️ Report is 7 commits behind head on develop.

Files with missing lines	Patch %	Lines
cluster/directory/static/directory.go	33.33%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3225      +/-   ##
===========================================
- Coverage    47.99%   47.91%   -0.08%     
===========================================
  Files          463      463              
  Lines        33727    33752      +25     
===========================================
- Hits         16187    16173      -14     
- Misses       16237    16271      +34     
- Partials      1303     1308       +5     

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[Copilot]

Pull request overview

This PR fixes static-directory routing initialization by building the router chain at static.NewDirectory creation time, so router-based behaviors (notably Tag Router) can take effect when no registry is used (Fixes #3222).

Changes:

• Call BuildRouterChain during static directory construction instead of only setting invokers on the default chain.
• Update multiple cluster tests to blank-import the Tag Router so router factories are registered during test runs.
• Tidy go.mod to mark github.com/cenkalti/backoff/v4 as a direct dependency.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
go.mod	Moves cenkalti/backoff/v4 to direct require (matches direct imports in code).
cluster/directory/static/directory.go	Builds router chain during static directory creation.
cluster/directory/static/directory_test.go	Adds Tag Router blank import for router-factory registration in tests.
cluster/cluster/available/cluster_invoker_test.go	Adds Tag Router blank import for router-factory registration in tests.
cluster/cluster/broadcast/cluster_invoker_test.go	Adds Tag Router blank import for router-factory registration in tests.
cluster/cluster/failback/cluster_test.go	Adds Tag Router blank import for router-factory registration in tests.
cluster/cluster/failfast/cluster_test.go	Adds Tag Router blank import for router-factory registration in tests.
cluster/cluster/failover/cluster_test.go	Adds Tag Router blank import for router-factory registration in tests.
cluster/cluster/failover/cluster_invoker_test.go	Adds Tag Router blank import for router-factory registration in tests.
cluster/cluster/failsafe/cluster_test.go	Adds Tag Router blank import for router-factory registration in tests.
cluster/cluster/forking/cluster_test.go	Adds Tag Router blank import for router-factory registration in tests.
cluster/cluster/zoneaware/cluster_invoker_test.go	Adds Tag Router blank import for router-factory registration in tests.

Comments suppressed due to low confidence (1)

cluster/directory/static/directory_test.go:34

• The tests in this file still only assert that List() returns all invokers; they don’t validate the regression fixed by this PR (router chain being built for static directories). Consider extending TestStaticDirList (or adding a new test) to configure tag-based routing (e.g., set dubbo.tag on invoker URLs and set invocation attachment dubbo.tag) and assert that List() returns only the routed subset. That would fail under the old implementation and pass with BuildRouterChain.

import (
	_ "dubbo.apache.org/dubbo-go/v3/cluster/router/tag"
	"dubbo.apache.org/dubbo-go/v3/common"
	"dubbo.apache.org/dubbo-go/v3/protocol/base"
	"dubbo.apache.org/dubbo-go/v3/protocol/invocation"
)

---

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[Copilot]

BuildRouterChain returns an error for len(invokers)==0, and NewDirectory logs it as an error. If NewDirectory can be called with an empty invoker list (e.g., during startup or transient states), this will introduce noisy error logs for a non-exceptional condition. Consider skipping router-chain building (and/or logging at debug level) when len(invokers)==0.

Suggested change

	err := dir.BuildRouterChain(invokers, url)
	if err != nil {
	logger.Error(err)
	if len(invokers) > 0 {
	if err := dir.BuildRouterChain(invokers, url); err != nil {
	logger.Error(err)
	}

[Copilot]

The new blank import of cluster/router/tag is duplicated within the same failover test package (it’s also imported in cluster_invoker_test.go). Only one blank import is needed per package; consider keeping it in a single shared _test.go (e.g., init_test.go) to avoid repetition.

Suggested change

_ "dubbo.apache.org/dubbo-go/v3/cluster/router/tag"

[Copilot]

NewDirectory now calls BuildRouterChain and only logs on error, but does not fall back to setting the router chain invokers. If chain.NewRouterChain(url) fails (e.g., no router factories registered), dir.RouterChain() remains the default empty chain.RouterChain{} with no invokers, so List() will route against an empty chain and can return an empty slice even though dir.invokers is populated. Consider always calling dir.RouterChain().SetInvokers(invokers) (or setting invokers on the existing chain) as a fallback when BuildRouterChain fails, so behavior matches the previous implementation when routing is unavailable.

Suggested change

	logger.Error(err)
	logger.Error(err)
	// Fallback: ensure any existing router chain still sees the invokers
	if routerChain := dir.RouterChain(); routerChain != nil {
	routerChain.SetInvokers(invokers)
	}