2 files changed, 107 insertions, 0 deletions
diff --git a/internal/exec/exec.go b/internal/exec/exec.go
new file mode 100644
index 0000000..87e861b
--- /dev/null
+++ b/internal/exec/exec.go
@@ -0,0 +1,38 @@
+package exec
+
+import (
+	"bytes"
+	"os/exec"
+)
+
+// Run executes a shell command with the given arguments and returns stdout, stderr, exit code, and any error encountered.
+func Run(name string, args ...string) (stdout, stderr string, exitCode int, err error) {
+	cmd := exec.Command(name, args...)
+
+	var stdoutBuf, stderrBuf bytes.Buffer
+	cmd.Stdout = &stdoutBuf
+	cmd.Stderr = &stderrBuf
+
+	err = cmd.Run()
+
+	stdout = stdoutBuf.String()
+	stderr = stderrBuf.String()
+
+	if err != nil {
+		if exitError, ok := err.(*exec.ExitError); ok {
+			exitCode = exitError.ExitCode()
+			// In this case, the error is just the non-zero exit code,
+			// which we've already captured. We return nil for err to indicate
+			// that the command actually ran and exited (even if non-zero).
+			err = nil
+		} else {
+			// This is a "real" error, e.g., binary not found
+			exitCode = -1
+			return stdout, stderr, exitCode, err
+		}
+	} else {
+		exitCode = 0
+	}
+
+	return stdout, stderr, exitCode, nil
+}
diff --git a/internal/exec/exec_test.go b/internal/exec/exec_test.go
new file mode 100644
index 0000000..4dc6505
--- /dev/null
+++ b/internal/exec/exec_test.go
@@ -0,0 +1,69 @@
+package exec
+
+import (
+	"testing"
+)
+
+func TestRun(t *testing.T) {
+	tests := []struct {
+		name           string
+		cmd            string
+		args           []string
+		wantStdout     string
+		wantStderr     string
+		wantExitCode   int
+		wantErr        bool
+	}{
+		{
+			name:         "success",
+			cmd:          "echo",
+			args:         []string{"hello world"},
+			wantStdout:   "hello world\n",
+			wantStderr:   "",
+			wantExitCode: 0,
+			wantErr:      false,
+		},
+		{
+			name:         "fail-exit-code",
+			cmd:          "ls",
+			args:         []string{"/non-existent-directory-12345"},
+			wantStdout:   "",
+			wantStderr:   "", // ls stderr varies by OS, but should not be empty usually.
+			wantExitCode: 2,  // Typical for ls non-existent
+			wantErr:      false,
+		},
+		{
+			name:         "fail-binary-not-found",
+			cmd:          "non-existent-command-12345",
+			args:         []string{},
+			wantStdout:   "",
+			wantStderr:   "",
+			wantExitCode: -1,
+			wantErr:      true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			stdout, stderr, exitCode, err := Run(tt.cmd, tt.args...)
+
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Run() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+
+			if exitCode != tt.wantExitCode {
+				t.Errorf("Run() exitCode = %v, want %v", exitCode, tt.wantExitCode)
+			}
+
+			if tt.name == "success" && stdout != tt.wantStdout {
+				t.Errorf("Run() stdout = %q, want %q", stdout, tt.wantStdout)
+			}
+			
+			// For ls error, we just check that stderr is not empty since exact text varies
+			if tt.name == "fail-exit-code" && stderr == "" {
+				t.Errorf("Run() stderr = %q, want non-empty", stderr)
+			}
+		})
+	}
+}