src/cmd/go/testdata/script/test_cache_coverpkg_bug.txt

# Test for bug where cached coverage profiles with -coverpkg can contain
# outdated line references when source files are modified.
# This reproduces the issue where coverage data from cache may reference
# lines that no longer exist in the updated source files.

[short] skip
[GODEBUG:gocacheverify=1] skip

# We're testing cache behavior, so start with a clean GOCACHE.
env GOCACHE=$WORK/cache

# Create a project structure with multiple packages
# proj/
#   some_func.go
#   some_func_test.go
#   sub/
#     sub.go
#     sub_test.go
#   sum/
#     sum.go

# Switch to the proj directory
cd proj

# Run tests with -coverpkg to collect coverage for all packages
go test -coverpkg=proj/... -coverprofile=cover1.out ./...
stdout 'coverage:'

# Verify the first coverage profile exists and has expected content
exists cover1.out
grep -q 'proj/sub/sub.go:' cover1.out

# Run again to ensure caching works
go test -coverpkg=proj/... -coverprofile=cover1_cached.out ./...
stdout '\(cached\)'
stdout 'coverage:'

# Note: Due to the bug, cached coverage profiles may have duplicate entries.
# The duplicate entries are the entries for the previous file structure and the new file structure.

# Now modify sub.go to change line structure - this will invalidate
# the cache for the sub package but not for the proj package.
cp ../sub_modified.go sub/sub.go

# After modifying sub.go, we should not have both old and new line references.
go test -coverpkg=proj/... -coverprofile=cover2.out ./...
stdout 'coverage:'

# With the bug present, we would see duplicate entries for the same lines.
# With the bug fixed, there should be no duplicate or stale entries in the coverage profile.
grep 'proj/sub/sub.go:' cover2.out
# The fix should ensure that only the new line format exists, not the old one
grep 'proj/sub/sub.go:4.2,4.35' cover2.out
# This should fail if the stale coverage line exists (the bug is present)
! grep 'proj/sub/sub.go:4.2,4.22' cover2.out

-- proj/go.mod --
module proj

go 1.21

-- proj/some_func.go --
package proj

import "proj/sum"

func SomeFunc(a, b int) int {
	if a == 0 && b == 0 {
		return 0
	}
	return sum.Sum(a, b)
}

-- proj/some_func_test.go --
package proj

import (
	"testing"
)

func Test_SomeFunc(t *testing.T) {
	t.Run("test1", func(t *testing.T) {
		result := SomeFunc(1, 1)
		if result != 2 {
			t.Errorf("Expected 2, got %d", result)
		}
	})
}

-- proj/sub/sub.go --
package sub

func Sub(a, b int) int {
	if a == 0 && b == 0 {
		return 0
	}
	return a - b
}

-- proj/sub/sub_test.go --
package sub

import (
	"testing"
)

func Test_Sub(t *testing.T) {
	t.Run("test_sub1", func(t *testing.T) {
		result := Sub(1, 1)
		if result != 0 {
			t.Errorf("Expected 0, got %d", result)
		}
	})
}

-- proj/sum/sum.go --
package sum

func Sum(a, b int) int {
	if a == 0 {
		return b
	}
	return a + b
}

-- sub_modified.go --
package sub

func Sub(a, b int) int {
	if a == 0 && b == 0 || a == -100 {
		return 0
	}
	return a - b
}