Fix script output dropping last line without trailing newline

NEXT_CHANGELOG.md

@@ -7,6 +7,7 @@
 ### CLI
 
 ### Bundles
+* Fix script output dropping last line without trailing newline ([#4995](https://github.com/databricks/cli/pull/4995))
 
 ### Dependency updates
 

acceptance/bundle/scripts/no-trailing-newline/databricks.yml

@@ -0,0 +1,6 @@
+bundle:
+  name: scripts_no_trailing_newline
+
+experimental:
+  scripts:
+    preinit: "python3 ./myscript.py"

acceptance/bundle/scripts/no-trailing-newline/myscript.py

@@ -0,0 +1,5 @@
+import sys
+
+sys.stdout.write("line 1\n")
+sys.stdout.write("line 2\n")
+sys.stdout.write("line without newline")

acceptance/bundle/scripts/no-trailing-newline/output.txt

@@ -0,0 +1,13 @@
+
+>>> [CLI] bundle validate
+Executing 'preinit' script
+line 1
+line 2
+line without newline
+Name: scripts_no_trailing_newline
+Target: default
+Workspace:
+  User: [USERNAME]
+  Path: /Workspace/Users/[USERNAME]/.bundle/scripts_no_trailing_newline/default
+
+Validation OK!

acceptance/bundle/scripts/no-trailing-newline/script

@@ -0,0 +1 @@
+trace $CLI bundle validate

bundle/scripts/scripts.go

@@ -51,10 +51,14 @@ func (m *script) Apply(ctx context.Context, b *bundle.Bundle) diag.Diagnostics {
 	cmdio.LogString(ctx, fmt.Sprintf("Executing '%s' script", m.scriptHook))
 
 	reader := bufio.NewReader(out)
-	line, err := reader.ReadString('\n')
-	for err == nil {
-		cmdio.LogString(ctx, strings.TrimSpace(line))
-		line, err = reader.ReadString('\n')
+	for {
+		line, err := reader.ReadString('\n')
+		if line != "" {
+			cmdio.LogString(ctx, strings.TrimSpace(line))
+		}
+		if err != nil {
+			break
+		}
 	}
 
 	err = cmd.Wait()

bundle/scripts/scripts_test.go

@@ -0,0 +1,50 @@
+package scripts_test
+
+import (
+	"runtime"
+	"testing"
+
+	"github.com/databricks/cli/bundle"
+	"github.com/databricks/cli/bundle/config"
+	"github.com/databricks/cli/bundle/scripts"
+	"github.com/databricks/cli/libs/cmdio"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestExecuteOutputWithoutTrailingNewline(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("skipping on windows")
+	}
+
+	dir := t.TempDir()
+	b := &bundle.Bundle{
+		BundleRootPath: dir,
+		Config: config.Root{
+			Experimental: &config.Experimental{
+				Scripts: map[config.ScriptHook]config.Command{
+					config.ScriptPreInit: "printf 'line1\nline2\nlast line without newline'",
+				},
+			},
+		},
+	}
+
+	ctx, stderr := cmdio.NewTestContextWithStderr(t.Context())
+	diags := bundle.Apply(ctx, b, scripts.Execute(config.ScriptPreInit))
+	require.NoError(t, diags.Error())
+
+	output := stderr.String()
+	assert.Contains(t, output, "line1")
+	assert.Contains(t, output, "line2")
+	assert.Contains(t, output, "last line without newline")
+}
+
+func TestExecuteNoScript(t *testing.T) {
+	b := &bundle.Bundle{
+		Config: config.Root{},
+	}
+
+	ctx, _ := cmdio.NewTestContextWithStderr(t.Context())
+	diags := bundle.Apply(ctx, b, scripts.Execute(config.ScriptPreInit))
+	require.NoError(t, diags.Error())
+}