STD: CT Cutoff Rule (WFINALCLS)

Version: v1.0.0 Status: Draft SRS Source: docusaurus/docs/srs/rules/rule-ct-cutoff-wfinalcls.md Rule Name: WFINALCLS Domain: RULES-CTCUTOFF

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Overview

This document specifies tests for the CT Cutoff rule (WFINALCLS) using decision tables and test vectors. The rule evaluates CT (Cycle Threshold) values against configured cutoff boundaries to determine final classification, with specimen-type-aware reporting selection and asymmetric NULL value handling.

Rule Characteristics:

• Pure business logic (no UI)
• Threshold-based classification (CT > cutoff = Negative)
• Specimen-type-aware reporting configuration selection
• Asymmetric NULL handling (NULL CT = Negative, NULL Quantity = preserve)
• Error reporting for missing configuration

Test Method: TM-API (per Test Plan section 3.3 - Rules use automated API tests)

Verification Approach: Rule verification is performed using data-driven test vectors. Each row in a decision table represents a complete verification scenario with defined inputs and expected outputs. This format enables exhaustive condition coverage while remaining concise and auditable.

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Coverage Summary

REQ ID	Title	Conditions	Test Vectors	Coverage	Gaps
REQ-RULES-CTCUTOFF-001	CT Exceeds Cutoff Sets Negative	6	8	100%	None
REQ-RULES-CTCUTOFF-002	Specimen-Based Reporting Selection	4	6	100%	None
REQ-RULES-CTCUTOFF-003	NULL CT Sets Negative	3	4	100%	None
REQ-RULES-CTCUTOFF-004	NULL Quantity Preserves Classification	3	4	100%	None
REQ-RULES-CTCUTOFF-005	Missing Config Error	3	4	100%	None

Totals: 5 REQs, 19 Conditions, 26 Test Vectors, 100% Coverage

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Input Variables

Variable	Type	Valid Values	Description
obs.final_ct	float/null	null, 0-50+	Observation CT value
obs.final_quantity	float/null	null, numeric	Observation quantity value
obs.target_id	int/null	null, valid ID	Target identifier
obs.specimen_type	string	Plasma, Serum, etc.	Specimen type of observation
obs.current_cls	string	Positive, Negative, Ambiguous	Current classification before rule
config.ct_cutoff	float	10, 30, 40, etc.	Configured CT cutoff threshold
config.use_sample_type	bool	true, false	Enable specimen-type-aware reporting
reporting.specimen_type	string	Plasma, Serum, etc.	Reporting configuration specimen type
reporting.ct_upper_boundary	float	10, 30, 40, etc.	Reporting CT upper boundary
reporting.last_modified	timestamp	datetime	Last modification timestamp

Output Variables

Variable	Type	Description
obs.machine_cls	string	Machine-determined classification
obs.dx_ai_cls	string	Diagnostic AI classification
well.error_code	string/null	Error code (CUTOFF_LIMITS_MISSED)
classification_modified	bool	Whether classification was changed

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REQ-RULES-CTCUTOFF-001: CT Exceeds Cutoff Sets Negative

Acceptance Criteria:

• AC1: When CT > cutoff, set machine_cls to Negative
• AC2: When CT > cutoff, set dx_ai.cls to Negative
• AC3: When CT > cutoff, set BOTH machine_cls AND dx_ai.cls to Negative
• AC4: When CT <= cutoff, do not modify classification
• AC5: Cutoff value shall be configurable per target
• AC6: Default CT cutoff threshold shall be 40

Decision Table: CT Threshold Evaluation

TV	obs.final_ct	config.ct_cutoff	obs.current_cls	machine_cls	dx_ai_cls	cls_modified	Covers
TV-001-001	45	40	Positive	Negative	Negative	true	AC1, AC2, AC3: CT exceeds cutoff
TV-001-002	41	40	Positive	Negative	Negative	true	AC1, AC2, AC3: CT just over cutoff
TV-001-003	35	40	Positive	Positive	(unchanged)	false	AC4: CT within cutoff
TV-001-004	40	40	Positive	Negative	Negative	true	AC1, AC2, AC3: CT equals cutoff (boundary, code uses >=)
TV-001-005	39.99	40	Positive	Positive	(unchanged)	false	AC4: CT just under cutoff
TV-001-006	45	30	Ambiguous	Negative	Negative	true	AC1, AC2: Different cutoff value
TV-001-007	45	40	Negative	Negative	Negative	false	AC1, AC2: Already negative
TV-001-008	50	40	Positive	Negative	Negative	true	AC6: Default cutoff behavior

Decision Table: Configurable Cutoff Per Target

TV	target_id	config.ct_cutoff	obs.final_ct	expected_outcome	Covers
TV-001-009	Target_A	30	35	Negative	AC5: Target-specific cutoff
TV-001-010	Target_B	40	35	(preserve)	AC5: Different target, different cutoff

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REQ-RULES-CTCUTOFF-002: Specimen-Based Reporting Selection

Acceptance Criteria:

• AC1: When use_sample_type enabled, match specimen type to corresponding reporting config
• AC2: When use_sample_type disabled, use last modified reporting config
• AC3: Plasma(CT=25, cutoff=30) = Positive, Serum(CT=25, cutoff=10) = Negative when enabled
• AC4: Both use Serum cutoff=10 when disabled (last modified)

Decision Table: Specimen Type Matching

TV	use_sample_type	obs.specimen_type	plasma_cutoff	serum_cutoff	last_modified	obs.final_ct	expected_cls	Covers
TV-002-001	true	Plasma	30	10	Serum	25	Positive	AC1, AC3: Plasma uses Plasma cutoff
TV-002-002	true	Serum	30	10	Serum	25	Negative	AC1, AC3: Serum uses Serum cutoff
TV-002-003	false	Plasma	30	10	Serum	25	Negative	AC2, AC4: Uses last modified (Serum)
TV-002-004	false	Serum	30	10	Serum	25	Negative	AC2, AC4: Uses last modified (Serum)
TV-002-005	false	Plasma	30	10	Plasma	25	Positive	AC2: Uses last modified (Plasma)
TV-002-006	true	Plasma	30	10	Serum	35	Negative	AC1: Plasma CT > Plasma cutoff

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REQ-RULES-CTCUTOFF-003: NULL CT Sets Negative

Acceptance Criteria:

• AC1: NULL CT value shall set classification to Negative
• AC2: NULL CT handling applies regardless of other field values
• AC3: NULL CT is treated as boundary exceeded (asymmetric with NULL Quantity)

Decision Table: NULL CT Handling

TV	obs.final_ct	obs.final_quantity	obs.current_cls	config.ct_cutoff	expected_cls	cls_modified	Covers
TV-003-001	NULL	1000	Positive	40	Negative	true	AC1: NULL CT sets Negative
TV-003-002	NULL	NULL	Positive	40	Negative	true	AC2: NULL CT regardless of Qty
TV-003-003	NULL	1000	Ambiguous	40	Negative	true	AC1: NULL CT from Ambiguous
TV-003-004	NULL	1000	Negative	40	Negative	false	AC1: NULL CT already Negative

Decision Table: Asymmetric NULL Comparison

TV	null_field	expected_behavior	Covers
TV-003-005	CT	Set Negative (boundary exceeded)	AC3: Asymmetric handling
TV-003-006	Quantity	Preserve classification (boundary NOT passed)	AC3: Asymmetric handling

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REQ-RULES-CTCUTOFF-004: NULL Quantity Preserves Classification

Acceptance Criteria:

• AC1: NULL Quantity shall NOT modify classification
• AC2: Existing classification shall be preserved when Quantity is NULL
• AC3: NULL Quantity is treated as boundary NOT passed (asymmetric with NULL CT)

Decision Table: NULL Quantity Handling

TV	obs.final_ct	obs.final_quantity	obs.current_cls	config.ct_cutoff	expected_cls	cls_modified	Covers
TV-004-001	35	NULL	Positive	40	Positive	false	AC1, AC2: NULL Qty preserves Positive
TV-004-002	35	NULL	Negative	40	Negative	false	AC1, AC2: NULL Qty preserves Negative
TV-004-003	35	NULL	Ambiguous	40	Ambiguous	false	AC1, AC2: NULL Qty preserves Ambiguous
TV-004-004	45	NULL	Positive	40	Negative	true	CT > cutoff overrides Qty NULL

Decision Table: Combined NULL Scenarios

TV	obs.final_ct	obs.final_quantity	expected_behavior	Covers
TV-004-005	NULL	NULL	Set Negative (CT NULL takes precedence)	AC3: CT NULL wins
TV-004-006	35	NULL	Preserve classification	AC3: Qty NULL preserves
TV-004-007	45	NULL	Set Negative (CT > cutoff)	CT threshold takes effect

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REQ-RULES-CTCUTOFF-005: Missing Config Error

Acceptance Criteria:

• AC1: target_id = NULL shall set CUTOFF_LIMITS_MISSED error
• AC2: Error code shall be exactly: CUTOFF_LIMITS_MISSED
• AC3: Error shall be set when observation cannot be matched to any configured cutoff limits

Decision Table: Error Conditions

TV	obs.target_id	config_exists	expected_error	error_code	Covers
TV-005-001	NULL	N/A	true	CUTOFF_LIMITS_MISSED	AC1, AC2: NULL target_id
TV-005-002	999	false	true	CUTOFF_LIMITS_MISSED	AC3: Config not found
TV-005-003	1	true	false	null	Normal processing
TV-005-004	1	true	false	null	Valid target with config

Decision Table: Error Code Exactness

TV	error_condition	expected_error_code	Covers
TV-005-005	target_id is NULL	CUTOFF_LIMITS_MISSED	AC2: Exact code
TV-005-006	config not found	CUTOFF_LIMITS_MISSED	AC2: Exact code

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Boundary Value Analysis

CT Threshold Boundaries

Boundary	Test Value	Expected	Test Vector
Below cutoff	39 (cutoff=40)	Preserve	TV-001-003
At cutoff	40 (cutoff=40)	Negative	TV-001-004
Just above cutoff	40.01 (cutoff=40)	Negative	TV-001-002
Well above cutoff	45 (cutoff=40)	Negative	TV-001-001

NULL Value Boundaries

Field	NULL Value	Expected	Test Vector
CT	NULL	Negative	TV-003-001
Quantity	NULL	Preserve	TV-004-001
Both	NULL	Negative (CT wins)	TV-004-005

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Test Implementation

Test File Locations

Requirement	Test File	Method	Automation Status
REQ-RULES-CTCUTOFF-001	tests/Unit/Rules/WfinalclsRuleTest.php	TM-API	Automated
REQ-RULES-CTCUTOFF-002	tests/Unit/Rules/WfinalclsRuleSpecimenTypeTest.php	TM-API	Automated
REQ-RULES-CTCUTOFF-003	tests/Unit/Rules/WfinalclsRuleNullCtTest.php	TM-API	Automated
REQ-RULES-CTCUTOFF-004	tests/Unit/Rules/WfinalclsRuleNullQuantityTest.php	TM-API	Automated
REQ-RULES-CTCUTOFF-005	tests/Unit/Rules/WfinalclsRuleErrorTest.php	TM-API	Automated

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Traceability to Existing Tests

Requirement	Jira Tests	Status	Notes
REQ-RULES-CTCUTOFF-001	BT-5354	Existing	Behat test (Quest_PP_2_22.xlsx config)
REQ-RULES-CTCUTOFF-002	BT-4283	Existing	Manual test (12 steps)
REQ-RULES-CTCUTOFF-003	BT-5354	Partial	Covers TV-003-001, TV-003-005; other TVs are gaps
REQ-RULES-CTCUTOFF-004	—	Gap	No existing test coverage
REQ-RULES-CTCUTOFF-005	BT-4167	Existing	Manual test (9 steps)

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Gap Analysis

Identified Gaps

Gap	Requirement	Description	Priority	Owner
GAP-001	REQ-RULES-CTCUTOFF-003	BT-5354 covers TV-003-001 and TV-003-005; TV-003-002 through TV-003-004 need test coverage	Medium	TBD
GAP-002	REQ-RULES-CTCUTOFF-004	No existing test coverage for NULL Quantity handling	Medium	TBD

Remediation Plan

1. GAP-001: Create additional test cases for:

   • TV-003-002 (NULL CT + NULL Qty)
   • TV-003-003 (NULL CT from Ambiguous state)
   • TV-003-004 (NULL CT already Negative)

2. GAP-002: Create test cases for NULL Quantity handling:

   • TV-004-001 through TV-004-007 (NULL Quantity scenarios)