STD: WCAF Rule (Multiple Control Failures)

Version: v1.0.0 Status: Draft SRS Source: docusaurus/docs/srs/rules/rule-wcaf.md Rule Name: WCAF Domain: RULES-WCAF

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Overview

This document specifies tests for the WCAF (Multiple Control Failures) rule using decision tables and test vectors. The rule detects when two or more control wells have failed in a run, marking affected wells for replating with an error message.

Rule Characteristics:

• Pure business logic (run-level QC rule)
• Threshold-based detection (2+ failures)
• Exclusion filtering (unknown mix wells)
• Dynamic clearing on error resolution
• Complements CONTROL_FAIL rule

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-WCAF-001	Detect and Mark Multiple Control Failures	8	12	100%	None
REQ-RULES-WCAF-002	Exclude Unknown Mix Wells from Failure Counting	4	8	100%	None
REQ-RULES-WCAF-003	Clear Error When Failures Reduce Below Threshold	5	10	100%	None

Totals: 3 REQs, 17 Conditions, 30 Test Vectors, 100% Coverage

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Input/Output Variables

Global Input Variables

Variable	Type	Valid Values	Description
control_wells	array	Well objects	Control wells in the run
well.status	enum	PASSED, FAILED	Control well QC status
well.mix_status	enum	known, unknown	Whether mix is identifiable
well.has_wcaf_error	bool	true, false	Whether WCAF error is applied
well.has_original_error	bool	true, false	Whether original control error exists
threshold	int	2 (default)	Number of failures to trigger WCAF

Global Output Variables

Variable	Type	Description
wcaf_triggered	bool	Whether WCAF rule fired
error_message	string?	"Well should be replated due to multiple qc errors" or null
affected_wells	array	Wells marked with WCAF error
wcaf_cleared	bool	Whether WCAF error was removed

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REQ-RULES-WCAF-001: Detect and Mark Multiple Control Failures

Input Variables

Variable	Type	Valid Values	Description
countable_failures	int	0, 1, 2, 3+	Control failures with known mix
total_controls	int	0, 1, 2+	Total control wells in run
threshold	int	2	Failure threshold

Output Variables

Variable	Type	Description
wcaf_triggered	bool	Rule fires when countable_failures >= threshold
error_message	string?	Error text or null
patient_samples_failed	bool	Patient samples fail by association

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Decision Table: Threshold Evaluation

TV	countable_failures	threshold	wcaf_triggered	error_message	Covers
TV-001-001	0	2	false	null	AC: 0 failures < threshold
TV-001-002	1	2	false	null	AC: 1 failure < threshold
TV-001-003	2	2	true	"Well should be replated due to multiple qc errors"	AC: Exactly 2 = threshold
TV-001-004	3	2	true	"Well should be replated due to multiple qc errors"	AC: 3 failures > threshold
TV-001-005	5	2	true	"Well should be replated due to multiple qc errors"	AC: Many failures > threshold

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Decision Table: Run-Level Scope

TV	total_controls	control_statuses	countable_failures	wcaf_triggered	Covers
TV-001-006	0	[]	0	false	AC: No controls = no trigger
TV-001-007	1	[FAILED]	1	false	AC: Single control failure
TV-001-008	3	[FAILED, FAILED, PASSED]	2	true	AC: 2 of 3 controls failed
TV-001-009	3	[PASSED, PASSED, PASSED]	0	false	AC: All controls pass

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Decision Table: Patient Sample Association

TV	wcaf_triggered	patient_wells_present	patient_samples_failed	Covers
TV-001-010	true	true	true	AC: Patients fail by association
TV-001-011	false	true	false	AC: No WCAF = patients unaffected
TV-001-012	true	false	N/A	AC: No patients present

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REQ-RULES-WCAF-002: Exclude Unknown Mix Wells from Failure Counting

Input Variables

Variable	Type	Valid Values	Description
well.status	enum	PASSED, FAILED	Control well QC status
well.mix_status	enum	known, unknown	Mix identifiability

Output Variables

Variable	Type	Description
counted_toward_threshold	bool	Whether failure counts

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Decision Table: Mix Status Exclusion

TV	well.status	well.mix_status	counted_toward_threshold	Covers
TV-002-001	FAILED	known	true	AC: Known mix failure counts
TV-002-002	FAILED	unknown	false	AC: Unknown mix excluded
TV-002-003	PASSED	known	false	AC: Passed well not counted
TV-002-004	PASSED	unknown	false	AC: Passed unknown not counted

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Decision Table: Combined Scenario - Mixed Known/Unknown

TV	known_failures	unknown_failures	countable_total	wcaf_triggered	Covers
TV-002-005	1	1	1	false	AC: 1 known + 1 unknown = 1 countable
TV-002-006	2	1	2	true	AC: 2 known + 1 unknown = 2 countable
TV-002-007	0	3	0	false	AC: 0 known + 3 unknown = 0 countable
TV-002-008	2	0	2	true	AC: 2 known + 0 unknown = 2 countable

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REQ-RULES-WCAF-003: Clear Error When Failures Reduce Below Threshold

Input Variables

Variable	Type	Valid Values	Description
initial_failures	int	2+	Failures before resolution
resolved_count	int	1+	Number of errors resolved
remaining_failures	int	0+	Failures after resolution
wcaf_error_present	bool	true	WCAF error exists before action

Output Variables

Variable	Type	Description
wcaf_cleared	bool	WCAF error removed
original_error_retained	bool	Original control error kept

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Decision Table: Re-evaluation After Resolution

TV	initial_failures	resolved_count	remaining_failures	wcaf_cleared	Covers
TV-003-001	2	1	1	true	AC: 2->1 = below threshold, clear
TV-003-002	3	1	2	false	AC: 3->2 = at threshold, keep
TV-003-003	3	2	1	true	AC: 3->1 = below threshold, clear
TV-003-004	4	2	2	false	AC: 4->2 = at threshold, keep
TV-003-005	2	0	2	false	AC: No resolution = keep

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Decision Table: WCAF Error Not Self-Counting

TV	control_failures	wcaf_errors_on_wells	counted_failures	Covers
TV-003-006	2	2	2	AC: WCAF errors not counted as failures
TV-003-007	1	1	1	AC: Only original errors counted

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Decision Table: Original Error Retention

TV	wcaf_cleared	original_error_present	original_error_retained	Covers
TV-003-008	true	true	true	AC: Original error kept when WCAF clears
TV-003-009	false	true	true	AC: Original error always retained
TV-003-010	true	false	N/A	AC: No original error to retain

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Error Handling Test Vectors

Decision Table: Edge Cases

TV	Scenario	Input State	Expected Behavior	Covers
TV-ERR-001	Undetermined status	well.status = UNKNOWN	Skip well, log warning	AC: Unable to determine status
TV-ERR-002	Empty run	control_wells = []	No trigger (0 < 2)	AC: No controls in run

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Traceability to Existing Tests

Requirement	Jira Tests	Automation Status	Config
REQ-RULES-WCAF-001	BT-5248 (14 TVs)	Automated	v2
REQ-RULES-WCAF-002	BT-5248, BT-5300	Automated	v2
REQ-RULES-WCAF-003	BT-5300 (4 TVs)	Automated	v2

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Gap Analysis

Identified Gaps

Gap	Requirement	Description	Priority	Remediation
None	-	All requirements have existing test coverage	-	-

Coverage Notes

1. BT-5248 covers core WCAF detection with 14 test vectors including threshold evaluation and unknown mix exclusion
2. BT-5300 covers error clearing scenarios with 4 test vectors for resolution behavior

All acceptance criteria from the SRS have corresponding test vectors. No gaps identified. Note: Both tests use v2 configs.