test: fix test execution and improve assertions

The logs tests had a critical issue preventing all test cases from
running. The production code used os.Exit(127) when syscall.Exec failed,
which terminated the entire test process after the first subtest
completed. This made gotestsum report failures and prevented
comprehensive test coverage.

Here is the error you can see in gotestsum previously:

```console
PASS pkg/cmd/tknpac/logs.TestLogs/good/show_logs (0.01s)
=== RUN   TestLogs
FAIL pkg/cmd/tknpac/logs.TestLogs (-1.00s)

=== Failed
=== FAIL: pkg/cmd/tknpac/logs TestLogs (unknown)
ok github.com/openshift-pipelines/pipelines-as-code/pkg/cmd/tknpac/logs
0.009s

DONE 2 tests, 1 failure in 0.011s
```

Changes made:
- Replace os.Exit with proper error return in showlogswithtkn()
- Add execFunc variable to make syscall.Exec mockable in tests
- Mock execFunc in tests to prevent process replacement
- Upgrade to gotest.tools/v3/assert for stronger assertions
- Fix duplicate test name causing gotestsum confusion
- Remove unused "shift" field and invalid test case
- Simplify test setup by removing unnecessary exec.LookPath

gotestsum, and all linting checks pass.

Assisted-by: Claude Sonnet 4.5 (via Claude Code)

Author: chmouel

pkg/cmd/tknpac/logs/exec_unix.go

@@ -0,0 +1,8 @@
+//go:build !windows
+
+package logs
+
+import "syscall"
+
+// defaultExecFunc replaces the current process with the given command (Unix only).
+var defaultExecFunc = syscall.Exec //nolint:gosec

pkg/cmd/tknpac/logs/exec_windows.go

@@ -0,0 +1,23 @@
+//go:build windows
+
+package logs
+
+import (
+	"fmt"
+	"os"
+	osexec "os/exec"
+)
+
+// defaultExecFunc runs the command as a subprocess on Windows,
+// since syscall.Exec (process replacement) is not available.
+var defaultExecFunc = func(argv0 string, argv, envv []string) error {
+	cmd := osexec.Command(argv0, argv[1:]...)
+	cmd.Env = envv
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	if err := cmd.Run(); err != nil {
+		return fmt.Errorf("failed to run command: %w", err)
+	}
+	return nil
+}

pkg/cmd/tknpac/logs/logs.go

@@ -7,7 +7,6 @@ import (
 	"os/exec"
 	"path/filepath"
 	"strings"
-	"syscall"
 
 	"github.com/AlecAivazis/survey/v2"
 	"github.com/jonboulle/clockwork"
@@ -54,6 +53,7 @@ type logOption struct {
 	limit      int
 	webBrowser bool
 	useLastPR  bool
+	execFunc   func(string, []string, []string) error
 }
 
 func Command(run *params.Run, ioStreams *cli.IOStreams) *cobra.Command {
@@ -124,6 +124,7 @@ func Command(run *params.Run, ioStreams *cli.IOStreams) *cobra.Command {
 				webBrowser: webBrowser,
 				tknPath:    tknPath,
 				useLastPR:  useLastPR,
+				execFunc:   defaultExecFunc,
 			}
 			return log(ctx, lopts)
 		},
@@ -240,7 +241,7 @@ func log(ctx context.Context, lo *logOption) error {
 	if lo.webBrowser {
 		return showLogsWithWebConsole(ctx, lo, replyName)
 	}
-	return showlogswithtkn(lo.tknPath, replyName, lo.cs.Info.Kube.Namespace)
+	return showlogswithtkn(lo.execFunc, lo.tknPath, replyName, lo.cs.Info.Kube.Namespace)
 }
 
 func showLogsWithWebConsole(ctx context.Context, lo *logOption, pr string) error {
@@ -257,11 +258,9 @@ func showLogsWithWebConsole(ctx context.Context, lo *logOption, pr string) error
 	return browser.OpenWebBrowser(ctx, lo.cs.Clients.ConsoleUI().DetailURL(prObj))
 }
 
-func showlogswithtkn(tknPath, pr, ns string) error {
-	//nolint: gosec
-	if err := syscall.Exec(tknPath, []string{tknPath, "pr", "logs", "-f", "-n", ns, pr}, os.Environ()); err != nil {
-		_, _ = fmt.Fprintf(os.Stderr, "Command finished with error: %v", err)
-		os.Exit(127)
+func showlogswithtkn(execFn func(string, []string, []string) error, tknPath, pr, ns string) error {
+	if err := execFn(tknPath, []string{tknPath, "pr", "logs", "-f", "-n", ns, pr}, os.Environ()); err != nil {
+		return fmt.Errorf("failed to exec tkn: %w", err)
 	}
 	return nil
 }

pkg/cmd/tknpac/logs/logs_test.go

@@ -1,7 +1,6 @@
 package logs
 
 import (
-	"os/exec"
 	"testing"
 
 	"github.com/jonboulle/clockwork"
@@ -33,7 +32,6 @@ func TestLogs(t *testing.T) {
 		wantErr          bool
 		repoName         string
 		currentNamespace string
-		shift            int
 		pruns            []*tektonv1.PipelineRun
 		useLastPR        bool
 	}{
@@ -42,15 +40,14 @@ func TestLogs(t *testing.T) {
 			wantErr:          false,
 			repoName:         "test",
 			currentNamespace: ns,
-			shift:            0,
 			pruns: []*tektonv1.PipelineRun{
 				tektontest.MakePRCompletion(cw, "test-pipeline", ns, completed, nil, map[string]string{
 					keys.Repository: "test",
 				}, 30),
 			},
 		},
 		{
-			name:             "good/show logs",
+			name:             "good/show logs with useLastPR",
 			wantErr:          false,
 			repoName:         "test",
 			currentNamespace: ns,
@@ -64,18 +61,6 @@ func TestLogs(t *testing.T) {
 				}, 30),
 			},
 		},
-		{
-			name:             "bad/shift",
-			wantErr:          true,
-			repoName:         "test",
-			currentNamespace: ns,
-			shift:            2,
-			pruns: []*tektonv1.PipelineRun{
-				tektontest.MakePRCompletion(cw, "test-pipeline", ns, completed, nil, map[string]string{
-					keys.Repository: "test",
-				}, 30),
-			},
-		},
 		{
 			name:             "bad/no prs",
 			wantErr:          true,
@@ -119,8 +104,6 @@ func TestLogs(t *testing.T) {
 			}
 			cs.Clients.SetConsoleUI(consoleui.FallBackConsole{})
 
-			tknPath, err := exec.LookPath("true")
-			assert.NilError(t, err)
 			io, _ := tcli.NewIOStream()
 			lopts := &logOption{
 				cs: cs,
@@ -130,16 +113,19 @@ func TestLogs(t *testing.T) {
 				},
 				repoName:  tt.repoName,
 				limit:     1,
-				tknPath:   tknPath,
+				tknPath:   "/fake/tkn",
 				ioStreams: io,
 				useLastPR: tt.useLastPR,
+				execFunc: func(_ string, _, _ []string) error {
+					return nil
+				},
 			}
 
-			err = log(ctx, lopts)
+			err := log(ctx, lopts)
 			if tt.wantErr {
-				if err == nil {
-					t.Errorf("log() wantError is true but no error has been set")
-				}
+				assert.Assert(t, err != nil, "expected an error but got none")
+			} else {
+				assert.NilError(t, err)
 			}
 		})
 	}