test(api): pin the merge-then-validate contract of the general settings endpoint

[marevol]

Why

ApiAdminGeneralAction.put$index (PUT /api/admin/general) had no unit test, and it is not a plain "store what was sent" update:

final EditBody newBody = new EditBody();
AdminGeneralAction.updateForm(fessConfig, newBody);                 // 1. load stored settings
BeanUtil.copyBeanToBean(body, newBody, CopyOptions::excludeNull);   // 2. overlay the request
validateApi(body, messages -> {                                     // 3. constraints on the RAW body
    if (AdminGeneralAction.isSpnegoNtlmPromptUnsupported(newBody)) {//    correlation on the MERGED one
        messages.addErrorsSpnegoPromptNtlmRequiresBasic("spnegoPromptNtlm");
    }
});
AdminGeneralAction.updateConfig(fessConfig, newBody);               // 4. store the MERGED body

The two shared halves (updateForm / updateConfig) are covered by AdminGeneralActionTest, and the integration suite's GeneralTests.crudTest() only calls testRead() (createTestParam/getUpdateMap are fail(); // Unreachable). The merge-then-validate glue in between — which body each of the four steps sees — was covered nowhere.

What this adds

src/test/java/org/codelibs/fess/app/web/api/admin/general/ApiAdminGeneralActionTest.java, 10 tests that drive the real put$index execute method (so the merge, the bean constraints and the correlated rule run in the action's own order):

Masked secret, both directions

• an omitted spnego_preauth_password keeps the stored secret — updateForm renders the ********** mask, excludeNull keeps it, updateConfig skips any all-mask value
• an explicitly empty spnego_preauth_password still deletes the stored value (deliberate: the SPNEGO library only falls back to a keytab when both the pre-auth user name and password are empty), because excludeNull excludes null and not ""
• a supplied password still replaces the stored one, so the mask guard cannot degenerate into "never write"

The merge fills in the request

• an omitted plain field keeps its stored value
• a body carrying only the four @Required fields is storable at all, which it can only be because the merge supplied the other three Integer fields updateConfig unboxes

The correlated rule reads the merged result

• stored sso.type=spnego + spnego.allow.basic=false + spnego.prompt.ntlm=true, request omits all three → still rejected with errors.spnego_prompt_ntlm_requires_basic
• negative control: the identical request is accepted when the stored combination is supported
• the request supplying the missing half (spnegoAllowBasic=true) is accepted

@Required is checked on the request

• a genuinely partial PUT is rejected with @Required on dayForCleanup, crawlingThreadCount, failureCountThreshold, csvFileEncoding, and nothing is written

Note on one detail

While writing this I checked the assumption that a partial PUT is rejected "before the correlation check ever runs". That is not what happens: ActionValidator.actuallyValidate collects the Hibernate violations, then calls the extra-validation lambda into the same message set, and throws once at the end. So the correlated rule does run on a partial PUT and contributes its message alongside the @Required ones. The last test pins that real behaviour (both messages in one response) rather than the assumed one.

Scope covered / not covered

Covered end to end: updateForm → excludeNull merge → validateApi (bean constraints + correlated rule) → updateConfig, plus the stored state afterwards and the Status.OK payload.

Not covered: LastaFlute's own translation of the thrown ValidationErrorException into an HTTP 400 response body, which happens in the API failure hook after the execute method has returned; and isAccessAllowed(), whose AccessTokenService binding is suppressed as in the sibling API action tests.

Anti-vacuity check

Each contract was verified against a deliberately broken copy of the action in a scratch worktree; every mutation is caught, and the mutations are killed by the tests that own that contract:

Mutation	Result
copyBeanToBean(body, newBody) (no excludeNull)	6 failures + 1 error / 10
isSpnegoNtlmPromptUnsupported(body) instead of newBody	2 failures / 10 — exactly the two correlation tests
updateConfig(fessConfig, body) instead of newBody	4 failures + 1 error / 10
validateApi(newBody, …) instead of body	2 failures / 10 — exactly the two @Required tests

Verification

mvn -o clean test -Dtest='ApiAdminGeneralActionTest,AdminGeneralActionTest,ApiAdminSchedulerActionTest,ApiAdminSearchlistActionTest'
Tests run: 34, Failures: 0, Errors: 0, Skipped: 0

ApiAdminGeneralActionTest alone: Tests run: 10, Failures: 0, Errors: 0, Skipped: 0. mvn formatter:format && mvn license:format produced no changes.

Test-only: git diff master --stat is the single new file.