### Go Coverage Profile Input Example

Source: https://context7.com/jandelgado/gcov2lcov/llms.txt

Example of the input format for Go coverage profiles, showing module path, line ranges, statement count, and execution count.

```text
mode: set
github.com/jandelgado/gcov2lcov/main.go:45.44,49.38 4 1
github.com/jandelgado/gcov2lcov/main.go:46.44,50.38 4 0
github.com/jandelgado/gcov2lcov/main.go:58.2,58.32  1 1
```

--------------------------------

### Install gcov2lcov from Source

Source: https://github.com/jandelgado/gcov2lcov/blob/master/README.md

Installs the gcov2lcov tool using Go modules. Ensure your Go environment is set up correctly.

```bash
go install github.com/jandelgado/gcov2lcov@latest
```

--------------------------------

### GitHub Actions Integration with `gcov2lcov-action`

Source: https://context7.com/jandelgado/gcov2lcov/llms.txt

Demonstrates how to integrate the gcov2lcov binary with GitHub Actions using the dedicated `gcov2lcov-action` or by installing the binary directly. This setup is for running tests with coverage and converting the output to lcov format for upload.

```yaml
# .github/workflows/coverage.yml
name: coverage
on: [push, pull_request]
jobs:
  coverage:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-go@v5
        with:
          go-version: '1.22'

      - name: Run tests with coverage
        run: go test -coverprofile=coverage.out ./...

      # Option A: use the dedicated action
      - name: Convert coverage to lcov
        uses: jandelgado/gcov2lcov-action@v1
        with:
          infile: coverage.out
          outfile: coverage.lcov

      # Option B: install binary directly and run manually
      - name: Install and run gcov2lcov
        run: |
          go install github.com/jandelgado/gcov2lcov@latest
          GOROOT=$(go env GOROOT) gcov2lcov -infile=coverage.out -outfile=coverage.lcov

      - name: Upload to Coveralls
        uses: coverallsapp/github-action@v2
        with:
          file: coverage.lcov
          format: lcov
```

--------------------------------

### LCOV Tracefile Output Example

Source: https://context7.com/jandelgado/gcov2lcov/llms.txt

Example of the generated lcov tracefile format, including test name, source file path, line execution counts, and total/hit line counts.

```text
TN:
SF:main.go
DA:45,1
DA:46,1
DA:47,1
DA:48,1
DA:49,1
DA:50,0
DA:58,1
LF:7
LH:6
end_of_record
```

--------------------------------

### Parse Go Coverage Line

Source: https://context7.com/jandelgado/gcov2lcov/llms.txt

Demonstrates parsing a single line from a Go coverage profile into file path and block data. Shows successful parsing and error cases for malformed input.

```go
// Input line format:
// github.com/jandelgado/gcov2lcov/main.go:6.14,8.3 2 1
//   └─ file path ─────────────────────────┘ └start┘└end┘ stmts covered

line := "github.com/jandelgado/gcov2lcov/main.go:6.14,8.3 2 1"
file, b, err := parseCoverageLine(line)
// file       => "github.com/jandelgado/gcov2lcov/main.go"
// b.startLine => 6,  b.startChar => 14
// b.endLine   => 8,  b.endChar   => 3
// b.statements => 2, b.covered   => 1
// err         => nil

// Error cases:
_, _, err = parseCoverageLine("main.go")           // missing colon separator → error
_, _, err = parseCoverageLine("main.go:A B")        // wrong number of space-separated parts → error
_, _, err = parseCoverageLine("main.go:6.14,8.3 X 1") // non-numeric statement count → error
```

--------------------------------

### Resolve Repo-Relative Path with `getCoverallsSourceFileName`

Source: https://context7.com/jandelgado/gcov2lcov/llms.txt

Walks up the directory tree from a given absolute path to find the VCS root (e.g., .git, .hg) and strips that prefix to produce a repository-relative path. This is the default path resolver for Coveralls compatibility. Falls back to the original path if no VCS root is found.

```go
// Assuming cwd is /home/user/projects/gcov2lcov (which contains .git)
name := getCoverallsSourceFileName("/home/user/projects/gcov2lcov/main.go")
// => "main.go"

name = getCoverallsSourceFileName("/home/user/projects/gcov2lcov/pkg/foo/bar.go")
// => "pkg/foo/bar.go"

// Falls back to original path if no VCS root found
name = getCoverallsSourceFileName("/tmp/standalone/main.go")
// => "/tmp/standalone/main.go"
```

--------------------------------

### Parse Go Coverage Profile with `parseCoverage`

Source: https://context7.com/jandelgado/gcov2lcov/llms.txt

Reads a Go coverage profile from an io.Reader, resolves file paths using go/build, and applies a path resolver function. Lines that cannot be parsed or whose packages cannot be resolved will emit a warning log and be skipped.

```go
import (
    "strings"
)

cov := `mode: set
github.com/jandelgado/gcov2lcov/main.go:6.14,8.3 2 1
github.com/jandelgado/gcov2lcov/main.go:7.14,9.3 2 0
github.com/jandelgado/gcov2lcov/main.go:10.1,11.10 2 2`

reader := strings.NewReader(cov)

// getCoverallsSourceFileName: strips repo root prefix → relative path (e.g. "main.go")
blocks, err := parseCoverage(reader, getCoverallsSourceFileName)
// blocks["main.go"] => []*block{ {6,14,8,3,2,1}, {7,14,9,3,2,0}, {10,1,11,10,2,2} }

// getSourceFileName: identity function → keeps absolute path as-is
blocks, err = parseCoverage(reader, getSourceFileName)
// blocks["/abs/path/to/main.go"] => []*block{...}
```

--------------------------------

### Pipe Coverage Data via Stdin/Stdout

Source: https://context7.com/jandelgado/gcov2lcov/llms.txt

Convert coverage data by piping the output of 'go test' directly to gcov2lcov's stdin.

```sh
# Pipe via stdin/stdout
go test -coverprofile=coverage.out ./... && cat coverage.out | gcov2lcov > coverage.lcov
```

--------------------------------

### Fix GOROOT Warnings

Source: https://context7.com/jandelgado/gcov2lcov/llms.txt

Prepend the GOROOT environment variable to resolve 'cannot find GOROOT directory' warnings, often encountered in CI environments.

```sh
# Fix "cannot find GOROOT directory" warnings in CI environments
GOROOT=$(go env GOROOT) gcov2lcov -infile=coverage.out -outfile=coverage.lcov
```

--------------------------------

### getCoverallsSourceFileName

Source: https://context7.com/jandelgado/gcov2lcov/llms.txt

Resolves a repository-relative path by walking up the directory tree to find the VCS root (e.g., .git) and stripping that prefix. This is the default path resolver for Coveralls compatibility.

```APIDOC
## `getCoverallsSourceFileName` — Resolve Repo-Relative Path

Walks up the directory tree from a given absolute path to find the VCS root (detected by the presence of `.git`, `.hg`, `.bzr`, or `.svn`), then strips that prefix to produce a repository-relative path. This is the default path resolver and produces paths compatible with Coveralls.

```go
// Assuming cwd is /home/user/projects/gcov2lcov (which contains .git)
name := getCoverallsSourceFileName("/home/user/projects/gcov2lcov/main.go")
// => "main.go"

name = getCoverallsSourceFileName("/home/user/projects/gcov2lcov/pkg/foo/bar.go")
// => "pkg/foo/bar.go"

// Falls back to original path if no VCS root found
name = getCoverallsSourceFileName("/tmp/standalone/main.go")
// => "/tmp/standalone/main.go"
```
```

--------------------------------

### Use Absolute Source Paths

Source: https://context7.com/jandelgado/gcov2lcov/llms.txt

Configure gcov2lcov to output absolute file paths in the lcov tracefile, which can be useful when the repository root is not consistently determined.

```sh
# Use absolute source paths (useful when repo root is ambiguous)
gcov2lcov -infile=coverage.out -outfile=coverage.lcov -use-absolute-source-path
```

--------------------------------

### parseCoverage

Source: https://context7.com/jandelgado/gcov2lcov/llms.txt

Parses a Go coverage profile from an io.Reader, resolves file paths, and returns a map of file paths to coverage blocks. Handles warnings for unparseable lines or unresolved packages.

```APIDOC
## `parseCoverage` — Parse a Full Coverage Profile

Reads an entire Go coverage profile from an `io.Reader`, resolves each file path using `go/build`, applies a path resolver function, and returns a map of resolved file paths to their coverage blocks. Lines that cannot be parsed or whose packages cannot be resolved emit a warning log and are skipped.

```go
import (
    "strings"
)

cov := `mode: set
github.com/jandelgado/gcov2lcov/main.go:6.14,8.3 2 1
github.com/jandelgado/gcov2lcov/main.go:7.14,9.3 2 0
github.com/jandelgado/gcov2lcov/main.go:10.1,11.10 2 2`

reader := strings.NewReader(cov)

// getCoverallsSourceFileName: strips repo root prefix → relative path (e.g. "main.go")
blocks, err := parseCoverage(reader, getCoverallsSourceFileName)
// blocks["main.go"] => []*block{ {6,14,8,3,2,1}, {7,14,9,3,2,0}, {10,1,11,10,2,2} }

// getSourceFileName: identity function → keeps absolute path as-is
blocks, err = parseCoverage(reader, getSourceFileName)
// blocks["/abs/path/to/main.go"] => []*block{...}
```
```

--------------------------------

### Convert Go Coverage to Lcov Format

Source: https://github.com/jandelgado/gcov2lcov/blob/master/README.md

Converts a Go coverage file to the lcov format. This is useful for uploading coverage reports to services like Coveralls. The output can be directed to a file or stdout.

```sh
go test -coverprofile=coverage.out && \
gcov2lcov -infile=coverage.out -outfile=coverage.lcov
```

--------------------------------

### Basic gcov2lcov Usage

Source: https://context7.com/jandelgado/gcov2lcov/llms.txt

Generate a coverage profile with 'go test' and then convert it to lcov format using gcov2lcov.

```sh
# Install from source
go install github.com/jandelgado/gcov2lcov@latest

# Basic usage: generate coverage profile then convert
go test -coverprofile=coverage.out ./...
gcov2lcov -infile=coverage.out -outfile=coverage.lcov
```

--------------------------------

### Lcov Tracefile Format Reference

Source: https://github.com/jandelgado/gcov2lcov/blob/master/README.md

Describes the structure of an lcov tracefile, including test name, source file information, function details, branch coverage, line execution counts, and summaries. This format is generated by tools like geninfo.

```text
TN:<test name>
SF:<absolute path to the source file>
FN:<line number of function start>,<function name>
FNDA:<execution count>,<function name>
FNF:<number of functions found> FNH:<number of function hit>
BRDA:<line number>,<block number>,<branch number>,<taken>
BRF:<number of branches found> BRH:<number of branches hit>
DA:<line number>,<execution count>[,<checksum>]
LH:<number of lines with a non-zero execution count> LF:<number of instrumented lines>
end_of_record
```

--------------------------------

### convertCoverage

Source: https://context7.com/jandelgado/gcov2lcov/llms.txt

The top-level conversion function that reads Go coverage data, converts it to lcov format, and writes the output. It combines parsing and writing into a single operation.

```APIDOC
## `convertCoverage` — End-to-End Conversion

The top-level conversion function. Reads a Go coverage profile from `io.Reader`, converts it to lcov format, and writes the result to `io.Writer`. Combines `parseCoverage` and `writeLcov` in a single call.

```go
import (
    "bytes"
    "strings"
)

cov := `mode: set
github.com/jandelgado/gcov2lcov/main.go:6.14,8.3 2 1
github.com/jandelgado/gcov2lcov/main.go:7.14,9.3 2 0
github.com/jandelgado/gcov2lcov/main.go:10.1,11.10 2 2`

in  := strings.NewReader(cov)
out := bytes.NewBufferString("")
err := convertCoverage(in, out, getCoverallsSourceFileName)

// out.String() =>
// TN:
// SF:main.go
// DA:6,1
// DA:7,1
// DA:8,1
// DA:9,0
// DA:10,2
// DA:11,2
// LF:6
// LH:5
// end_of_record
```
```

--------------------------------

### End-to-End Conversion with `convertCoverage`

Source: https://context7.com/jandelgado/gcov2lcov/llms.txt

The top-level conversion function that reads a Go coverage profile, converts it to lcov format, and writes the result to an io.Writer. It combines `parseCoverage` and `writeLcov` in a single call.

```go
import (
    "bytes"
    "strings"
)

cov := `mode: set
github.com/jandelgado/gcov2lcov/main.go:6.14,8.3 2 1
github.com/jandelgado/gcov2lcov/main.go:7.14,9.3 2 0
github.com/jandelgado/gcov2lcov/main.go:10.1,11.10 2 2`

in  := strings.NewReader(cov)
out := bytes.NewBufferString("")
err := convertCoverage(in, out, getCoverallsSourceFileName)

// out.String() =>
// TN:
// SF:main.go
// DA:6,1
// DA:7,1
// DA:8,1
// DA:9,0
// DA:10,2
// DA:11,2
// LF:6
// LH:5
// end_of_record
```

--------------------------------

### Write lcov Record with `writeLcovRecord`

Source: https://context7.com/jandelgado/gcov2lcov/llms.txt

Writes a single lcov record for a source file to an io.StringWriter. It aggregates per-block covered counts into per-line counts and emits sorted `DA` entries followed by `LF`/`LH` summary lines.

```go
import (
    "bytes"
    "bufio"
)

blocks := []*block{
    {startLine: 6, endLine: 8, covered: 1},  // lines 6,7,8 each get +1
    {startLine: 7, endLine: 9, covered: 0},  // lines 7,8,9 each get +0
}
buf := bytes.NewBufferString("")
w   := bufio.NewWriter(buf)
err := writeLcovRecord("main.go", blocks, w)
w.Flush()
// Output:
// TN:
// SF:main.go
// DA:6,1
// DA:7,1
// DA:8,1
// DA:9,0
// LF:4
// LH:3
// end_of_record
```

--------------------------------

### Set GOROOT for gcov2lcov

Source: https://github.com/jandelgado/gcov2lcov/blob/master/README.md

If you encounter 'cannot find GOROOT directory' errors, explicitly set the GOROOT environment variable before running gcov2lcov. This ensures the tool can locate necessary Go build information.

```sh
GOROOT=$(go env GOROOT) gcov2lcov -infile=coverage.out -outfile=coverage.lcov
```

--------------------------------

### writeLcovRecord

Source: https://context7.com/jandelgado/gcov2lcov/llms.txt

Writes a single lcov record for a source file to an io.StringWriter. It aggregates block coverage counts into line counts and emits sorted DA entries with LF/LH summary lines.

```APIDOC
## `writeLcovRecord` — Write a Single File's lcov Record

Writes one lcov record for a single source file to an `io.StringWriter`. Aggregates per-block covered counts into per-line counts (a line covered by multiple overlapping blocks sums their counts), then emits sorted `DA` entries followed by `LF`/`LH` summary lines.

```go
import (
    "bytes"
    "bufio"
)

blocks := []*block{
    {startLine: 6, endLine: 8, covered: 1},  // lines 6,7,8 each get +1
    {startLine: 7, endLine: 9, covered: 0},  // lines 7,8,9 each get +0
}
buf := bytes.NewBufferString("")
w   := bufio.NewWriter(buf)
err := writeLcovRecord("main.go", blocks, w)
w.Flush()
// Output:
// TN:
// SF:main.go
// DA:6,1
// DA:7,1
// DA:8,1
// DA:9,0
// LF:4
// LH:3
// end_of_record
```
```

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