Go: `codegraph affected` never matches `*_test.go` — the CLI-local `isTestFile` duplicates and diverges from `search/query-utils.ts`

[nextCY]

Env: codegraph 1.5.0 (win32-x64).

codegraph affected reports no tests for a Go file that has a sibling _test.go. It exits 0 with a plausible message, so it reads as "this code has no test coverage" rather than as a failure.

Repro

Two-file Go project:

// go.mod: module example.com/demo

// math.go
package demo
func Add(a, b int) int { return a + b }

// math_test.go
package demo
import "testing"
func TestAdd(t *testing.T) { if Add(1, 2) != 3 { t.Fatal("boom") } }

$ codegraph init .
● 5 nodes, 4 edges in 271ms

$ codegraph affected math.go
ℹ No test files affected by the changed files.          # <- expected math_test.go

$ codegraph affected --filter '*_test.go' math.go
Affected test files (1):
  math_test.go                                          # <- found, so only the predicate is wrong

The graph itself knows perfectly well:

$ codegraph node Add
**Called by ←** TestAdd (math_test.go:5)

Same shape in TypeScript works with the default glob, which isolates it to the Go naming convention:

# math.ts + math.test.ts
$ codegraph affected math.ts
Affected test files (1):
  math.test.ts

Root cause

The affected command defines its own isTestFile inline instead of importing the shared one. In src/bin/codegraph.ts, inside the affected action:

const defaultTestPatterns = [
    /\.spec\./, /\.test\./, /\/__tests__\//, /\/tests?\//, /\/e2e\//, /\/spec\//,
];
function isTestFile(filePath) {
    if (customFilter) return customFilter.test(filePath);
    return defaultTestPatterns.some(p => p.test(filePath));
}

All six are JS/TS conventions. Go uses an underscore suffix — math_test.go — which matches none of them (/\.test\./ needs a dot on both sides; Go has _test.).

Meanwhile src/search/query-utils.ts already ships a correct multi-language isTestFile, which is what explore / node / search use:

/[._-](test|tests|spec|specs)\.[a-z0-9]+$/.test(lowerName)   // math_test.go, math.test.ts, math-spec.rb
lowerName.startsWith('test_')                                 // test_math.py
/(?:Test|Tests|TestCase|Tester|Spec|Specs)\.[A-Za-z0-9]+$/    // MathTest.kt, MathTests.swift

Its comments name foo_test.go explicitly, and it even guards against false positives like latest.kt / manifest.kt. So affected is the only blind path — it never asks the shared helper.

Probably why this survived: affected is CLI-only (there is no codegraph_affected MCP tool), so agents never exercise it, and agents are the primary consumer.

Secondary: --filter uncovers an unrelated over-reporting problem

On a real-world Go repo (a few hundred files), working around the bug with --filter '*_test.go' swings the other way — the result includes test files from packages with no relationship to the changed file.

--filter only swaps the is-this-a-test predicate; the dependent BFS still runs at the default --depth 5, and five hops of transitive dependents reach most of a Go tree. The broken default glob was masking this, so the two problems cancelled into empty-but-believable output.

Suggested fix

Delete the local defaultTestPatterns / isTestFile in src/bin/codegraph.ts and import isTestFile from src/search/query-utils.ts. That one already covers Go / Python / Java / Kotlin / Swift / C# / Scala, so this is a one-line import rather than a second pattern list to keep in sync.

For the second half, a smaller default --depth for affected — or a note that 5 is very wide for compiled languages where package-level dependents fan out fast — would make the output usable.

[maxmilian]

Confirmed on upstream/main (c65d56c) — and the fix you describe is already open as #1273, which is probably the most useful thing I can add here.

#1273 ("fix(affected): recognize root-level test files", opened 2026-07-13) does exactly what this issue asks for: it deletes the six inline patterns and calls the shared predicate.

-      const defaultTestPatterns = [ /\.spec\./, /\.test\./, ... ];
-      function isTestFile(filePath: string): boolean {
-        if (customFilter) return customFilter.test(filePath);
-        return defaultTestPatterns.some(p => p.test(filePath));
+      function matchesTestFile(filePath: string): boolean {
+        if (customFilter) return customFilter(filePath);
+        return isDefaultTestFile(filePath);   // from ../search/query-utils
       }

It fixes your Go case, but nothing about it says so — the title and tests are about a root-level tests/ Python directory, so this issue and that PR read as unrelated. The Go fix falls out of the shared predicate's separator rule, /[._-](test|tests|spec|specs)\.[a-z0-9]+$/, which math_test.go matches on the _.

I ran both predicates against the same inputs at c65d56c rather than reasoning from the regexes:

path	inline (affected)	shared (query-utils)
math_test.go	false	true
tests/test_math_utils.py	false	true
FooTest.kt	false	true
math.test.ts	true	true
math.go	false	false

Three things that adds to the report:

• Go is not the only language affected. FooTest.kt / BarTests.swift / BazSpec.scala / QuxTestCase.java all miss too — the inline list has no CamelCase-suffix rule at all. So affected silently reports "no tests" for most of the JVM and Swift ecosystems, not just Go.
• tests/test_math_utils.py fails for a second, independent reason: /\/tests?\// requires slashes on both sides, so a repo-root tests/ directory never matches. That is fix(affected): recognize root-level test files #1273's original case, and it is the same one-line-import fix.
• No over-matching in the other direction: math.go stays false on both, so swapping the predicate doesn't turn ordinary source files into "tests".

So I don't think this needs a second PR — it needs #1273 reviewed. It has been open three weeks with no review, is +26/−28 across one source file and one test file, and closes at least two issues rather than one. @colbymchenry if it helps, the smallest possible check is the table above: the shared predicate is already what explore / node / search use, so this is removing a divergence rather than introducing a rule.

One thing #1273 does not carry is a Go regression test — its two new tests are Python. Worth adding math.go + math_test.go to __tests__/cli-affected-paths.test.ts before merge, since Go is the shape reported here. Happy to send that as a follow-up commit to #1273 if @Jseca666 would rather not reopen the branch, or leave it to whoever reviews.

(Checked against upstream/main at c65d56c; the inline defaultTestPatterns block is still live at src/bin/codegraph.ts:2153.)