Improve Test Coverage

This skill analyzes test coverage data from tobari and helps improve test coverage incrementally.

Prerequisites

Ensure you have run tests with tobari enabled:

GOFLAGS="$(tobari flags)" go test ./...

How to Read Coverage Data

1. •Check if TOBARI_COVERDIR environment variable is set:
   bash

   echo $TOBARI_COVERDIR
   

2. •If set, read $TOBARI_COVERDIR/tobari/tobari.toon
3. •If not set or empty, read ./tobari/tobari.toon from current directory

TOON Format Parsing

The tobari.toon file uses Token-Oriented Object Notation format:

TestName[N]{FileName,StartLine,StartCol,EndLine,EndCol,StatementCount,Count}:
	/path/to/file.go,7,24,9,2,1,4
	/path/to/file.go,11,29,12,22,1,0

• •Top-level key is the test name (e.g., Add corresponds to TestAdd function)
• •[N] indicates the number of entries
• •Each indented line (starting with tab) is a coverage entry with comma-separated values:
  • •FileName: source file path
  • •StartLine, StartCol: start position
  • •EndLine, EndCol: end position
  • •StatementCount: number of statements in this block
  • •Count: execution count (0 = not covered)

Calculate Current Coverage

1. •

   Collect all unique coverage entries across all tests:

   • •Key = FileName:StartLine:StartCol:EndLine:EndCol
   • •Track: StatementCount, MaxCount (highest Count across all tests)
2. •

   Calculate coverage rate:

   code

   TotalStatements = sum of all StatementCount values
   CoveredStatements = sum of StatementCount where MaxCount > 0
   CoverageRate = CoveredStatements / TotalStatements * 100
   

3. •

   Report to user:

   code

   Current coverage: XX.X% (Y of Z statements covered)
   

Improve Coverage Incrementally

Set Target and Improve

1. •

   Set target: CurrentCoverage + 5% (capped at 100%)

2. •

   Find uncovered code blocks (where Count = 0 for all tests):

   • •Read the source file at those locations
   • •Understand what code path leads to that block
   • •Determine what test input would exercise that code
3. •

   Implement improvements:

   • •Add new test cases or modify existing ones
   • •Follow existing test patterns in the codebase
   • •Use table-driven tests when appropriate for Go
4. •

   Run tests with tobari to verify coverage improved:

   bash

   GOFLAGS="$(tobari flags)" go test ./...
   

5. •

   Re-read tobari.toon and calculate new coverage

Report and Confirm

After each improvement cycle:

1. •

   Show the user:

   • •Previous coverage rate
   • •New coverage rate
   • •What was added/changed
2. •

   Use AskUserQuestion:

   • •Question: "Coverage improved from X% to Y%. How would you like to proceed?"
   • •Options:
     • •"Continue improving (+5% more)"
     • •"Skip confirmations and continue to Z%" (where Z is a target like 80%, 90%, 100%)
     • •"Stop here"
3. •

   If user selects "Skip confirmations":

   • •Ask for target percentage if not specified
   • •Continue improving without confirmation until target is reached or no more improvements possible
4. •

   If user selects "Continue", repeat from "Set Target and Improve"

Important Guidelines

• •Focus on meaningful coverage that tests actual behavior, not just line hits
• •Consider edge cases: error paths, boundary conditions, nil/empty inputs
• •When adding tests, follow existing patterns in the codebase
• •Prefer table-driven tests for Go code when testing multiple inputs
• •Don't add tests just to hit lines - ensure tests verify correct behavior
• •If a code path is intentionally unreachable (dead code), suggest removing it instead of adding tests