chore(progress): fix showing cursor after rendering (#1901)

Although we have a `defer cursor.Show()` statement, it wouldn't actually get written to `out` because we never called `Flush()`. 

This change ensures that all buffered writes get written to `out` at the end of the invocation.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

Author: efekarakus

internal/pkg/term/progress/render.go

@@ -40,6 +40,8 @@ func NestedRenderOptions(opts RenderOptions) RenderOptions {
 // Render stops when there the ctx is canceled or r is done listening to new events.
 // While Render is executing, the terminal cursor is hidden and updates are written in-place.
 func Render(ctx context.Context, out FileWriteFlusher, r DynamicRenderer) error {
+	defer out.Flush() // Make sure every buffered text in out is written before exiting.
+
 	cursor := cursor.NewWithWriter(out)
 	cursor.Hide()
 	defer cursor.Show()

internal/pkg/term/progress/render_test.go

@@ -4,6 +4,7 @@
 package progress
 
 import (
+	"bytes"
 	"context"
 	"io"
 	"strings"
@@ -33,17 +34,33 @@ func (m *mockDynamicRenderer) Done() <-chan struct{} {
 }
 
 type mockFileWriteFlusher struct {
-	io.Writer
+	buf     bytes.Buffer
+	wrapper io.Writer
+}
+
+func (m *mockFileWriteFlusher) Write(p []byte) (n int, err error) {
+	return m.buf.Write(p)
 }
 
 func (m *mockFileWriteFlusher) Fd() uintptr {
 	return 0
 }
 
 func (m *mockFileWriteFlusher) Flush() error {
+	if _, err := m.buf.WriteTo(m.wrapper); err != nil {
+		return err
+	}
 	return nil
 }
 
+type mockFileWriter struct {
+	io.Writer
+}
+
+func (m *mockFileWriter) Fd() uintptr {
+	return 0
+}
+
 func TestRender(t *testing.T) {
 	t.Run("stops the renderer when context is canceled", func(t *testing.T) {
 		t.Parallel()
@@ -56,7 +73,7 @@ func TestRender(t *testing.T) {
 			done:    make(chan struct{}),
 		}
 		out := &mockFileWriteFlusher{
-			Writer: actual,
+			wrapper: actual,
 		}
 
 		// WHEN
@@ -76,7 +93,7 @@ func TestRender(t *testing.T) {
 			done:    done,
 		}
 		out := &mockFileWriteFlusher{
-			Writer: actual,
+			wrapper: actual,
 		}
 		go func() {
 			<-time.After(350 * time.Millisecond)
@@ -94,7 +111,7 @@ func TestRender(t *testing.T) {
 		// 2. Write "hi\n", erase the line, and move the cursor up (Repeated x3 times)
 		// 3. The <-ctx.Done() is called so we should write one last time "hi\n" and the cursor should be shown.
 		wanted := new(strings.Builder)
-		wantedFW := &mockFileWriteFlusher{
+		wantedFW := &mockFileWriter{
 			Writer: wanted,
 		}
 		c := cursor.NewWithWriter(wantedFW)