chore: avoid trying to stream data

`profile.Parse` always call `io.ReadAll` so avoid the trouble and a
goroutine and do it ourselves.

Add some limited testing (testing the parsed stack is volatile and not
really feasible).

modules/process/manager_stacktraces_test.go

@@ -0,0 +1,93 @@
+// Copyright 2025 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package process
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestProcessStacktraces(t *testing.T) {
+	_, _, finish := GetManager().AddContext(context.Background(), "Normal process")
+	defer finish()
+	parentCtx, _, finish := GetManager().AddContext(context.Background(), "Children normal process")
+	defer finish()
+	_, _, finish = GetManager().AddContext(parentCtx, "Children process")
+	defer finish()
+	_, _, finish = GetManager().AddTypedContext(context.Background(), "System process", SystemProcessType, true)
+	defer finish()
+
+	t.Run("No flat with no system process", func(t *testing.T) {
+		processes, processCount, _, err := GetManager().ProcessStacktraces(false, true)
+		require.NoError(t, err)
+		assert.EqualValues(t, 4, processCount)
+		assert.Len(t, processes, 2)
+
+		assert.EqualValues(t, "Children normal process", processes[0].Description)
+		assert.EqualValues(t, NormalProcessType, processes[0].Type)
+		assert.Empty(t, processes[0].ParentPID)
+		assert.Len(t, processes[0].Children, 1)
+
+		assert.EqualValues(t, "Children process", processes[0].Children[0].Description)
+		assert.EqualValues(t, processes[0].PID, processes[0].Children[0].ParentPID)
+
+		assert.EqualValues(t, "Normal process", processes[1].Description)
+		assert.EqualValues(t, NormalProcessType, processes[1].Type)
+		assert.Empty(t, processes[1].ParentPID)
+		assert.Empty(t, processes[1].Children)
+	})
+
+	t.Run("Flat with no system process", func(t *testing.T) {
+		processes, processCount, _, err := GetManager().ProcessStacktraces(true, true)
+		require.NoError(t, err)
+		assert.EqualValues(t, 4, processCount)
+		assert.Len(t, processes, 3)
+
+		assert.EqualValues(t, "Children process", processes[0].Description)
+		assert.EqualValues(t, NormalProcessType, processes[0].Type)
+		assert.EqualValues(t, processes[1].PID, processes[0].ParentPID)
+		assert.Empty(t, processes[0].Children)
+
+		assert.EqualValues(t, "Children normal process", processes[1].Description)
+		assert.EqualValues(t, NormalProcessType, processes[1].Type)
+		assert.Empty(t, processes[1].ParentPID)
+		assert.Empty(t, processes[1].Children)
+
+		assert.EqualValues(t, "Normal process", processes[2].Description)
+		assert.EqualValues(t, NormalProcessType, processes[2].Type)
+		assert.Empty(t, processes[2].ParentPID)
+		assert.Empty(t, processes[2].Children)
+	})
+
+	t.Run("System process", func(t *testing.T) {
+		processes, processCount, _, err := GetManager().ProcessStacktraces(false, false)
+		require.NoError(t, err)
+		assert.EqualValues(t, 4, processCount)
+		assert.Len(t, processes, 4)
+
+		assert.EqualValues(t, "System process", processes[0].Description)
+		assert.EqualValues(t, SystemProcessType, processes[0].Type)
+		assert.Empty(t, processes[0].ParentPID)
+		assert.Empty(t, processes[0].Children)
+
+		assert.EqualValues(t, "Children normal process", processes[1].Description)
+		assert.EqualValues(t, NormalProcessType, processes[1].Type)
+		assert.Empty(t, processes[1].ParentPID)
+		assert.Len(t, processes[1].Children, 1)
+
+		assert.EqualValues(t, "Normal process", processes[2].Description)
+		assert.EqualValues(t, NormalProcessType, processes[2].Type)
+		assert.Empty(t, processes[2].ParentPID)
+		assert.Empty(t, processes[2].Children)
+
+		// This is the "main" pid, testing code always runs in a goroutine.
+		assert.EqualValues(t, "(unassociated)", processes[3].Description)
+		assert.EqualValues(t, NoneProcessType, processes[3].Type)
+		assert.Empty(t, processes[3].ParentPID)
+		assert.Empty(t, processes[3].Children)
+	})
+}