fix: restore output for add and remove subcommands, add tests (#348)

In our upgrade to bubbletea v2, we didn't catch that we lost the output
for dbc add and remove. Whereas dbc 0.2.0 prints like this,

```sh
$ dbc add mysql
added mysql to driver list
use `dbc sync` to install the drivers in the list
```

git main prints like this (nothing):

```sh
$ dbc add mysql
```

This patch restores the output and adds regression tests for both
subcommands.

Author: amoeba

cmd/dbc/add.go

@@ -75,6 +75,7 @@ type addModel struct {
 	Path   string
 	Pre    bool
 	list   DriversList
+	result string
 }
 
 func (m addModel) Init() tea.Cmd {
@@ -212,7 +213,8 @@ func (m addModel) Init() tea.Cmd {
 func (m addModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	switch msg := msg.(type) {
 	case string:
-		return m, tea.Sequence(tea.Println(msg), tea.Quit)
+		m.result = msg
+		return m, tea.Quit
 	default:
 		bm, cmd := m.baseModel.Update(msg)
 		m.baseModel = bm.(baseModel)
@@ -221,4 +223,11 @@ func (m addModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	}
 }
 
+func (m addModel) FinalOutput() string {
+	if m.status != 0 {
+		return ""
+	}
+	return m.result
+}
+
 func (m addModel) View() tea.View { return tea.NewView("") }

cmd/dbc/add_test.go

@@ -142,7 +142,9 @@ func TestAddRepeatedNewWithConstraint(t *testing.T) {
 		m, err = p.Run()
 		require.NoError(t, err)
 		assert.Equal(t, 0, m.(HasStatus).Status())
-		assert.Contains(t, out.String(), "old constraint: any; new constraint: >=1.0.0")
+		if fo, ok := m.(HasFinalOutput); ok {
+			assert.Contains(t, fo.FinalOutput(), "old constraint: any; new constraint: >=1.0.0")
+		}
 
 		data, err := os.ReadFile(filepath.Join(dir, "dbc.toml"))
 		require.NoError(t, err)
@@ -409,3 +411,60 @@ func (suite *SubcommandTestSuite) TestAddCompleteRegistryFailure() {
 	suite.Contains(out, "error getting driver list")
 	suite.Contains(out, "network unreachable")
 }
+
+func (suite *SubcommandTestSuite) TestAddOutput() {
+	m := InitCmd{Path: filepath.Join(suite.tempdir, "dbc.toml")}.GetModel()
+	suite.runCmd(m)
+
+	m = AddCmd{
+		Path:   filepath.Join(suite.tempdir, "dbc.toml"),
+		Driver: []string{"test-driver-1"},
+	}.GetModelCustom(
+		baseModel{getDriverRegistry: getTestDriverRegistry, downloadPkg: downloadTestPkg})
+
+	out := suite.runCmd(m)
+	suite.Contains(out, "added test-driver-1 to driver list")
+	suite.Contains(out, "use `dbc sync` to install the drivers in the list")
+}
+
+func (suite *SubcommandTestSuite) TestAddMultipleOutput() {
+	m := InitCmd{Path: filepath.Join(suite.tempdir, "dbc.toml")}.GetModel()
+	suite.runCmd(m)
+
+	m = AddCmd{
+		Path:   filepath.Join(suite.tempdir, "dbc.toml"),
+		Driver: []string{"test-driver-1", "test-driver-2"},
+	}.GetModelCustom(
+		baseModel{getDriverRegistry: getTestDriverRegistry, downloadPkg: downloadTestPkg})
+
+	out := suite.runCmd(m)
+	suite.Contains(out, "added test-driver-1 to driver list")
+	suite.Contains(out, "added test-driver-2 to driver list")
+	suite.Contains(out, "use `dbc sync` to install the drivers in the list")
+}
+
+func (suite *SubcommandTestSuite) TestAddReplacingDriverOutput() {
+	m := InitCmd{Path: filepath.Join(suite.tempdir, "dbc.toml")}.GetModel()
+	suite.runCmd(m)
+
+	// Add driver without constraint
+	m = AddCmd{
+		Path:   filepath.Join(suite.tempdir, "dbc.toml"),
+		Driver: []string{"test-driver-1"},
+	}.GetModelCustom(
+		baseModel{getDriverRegistry: getTestDriverRegistry, downloadPkg: downloadTestPkg})
+	suite.runCmd(m)
+
+	// Add same driver with constraint and verify replacement message
+	m = AddCmd{
+		Path:   filepath.Join(suite.tempdir, "dbc.toml"),
+		Driver: []string{"test-driver-1>=1.0.0"},
+	}.GetModelCustom(
+		baseModel{getDriverRegistry: getTestDriverRegistry, downloadPkg: downloadTestPkg})
+
+	out := suite.runCmd(m)
+	suite.Contains(out, "replacing existing driver test-driver-1")
+	suite.Contains(out, "old constraint: any; new constraint: >=1.0.0")
+	suite.Contains(out, "added test-driver-1 to driver list")
+	suite.Contains(out, "with constraint >=1.0.0")
+}

cmd/dbc/remove.go

@@ -54,7 +54,8 @@ type removeModel struct {
 	Driver string
 	Path   string
 
-	list DriversList
+	list   DriversList
+	result string
 }
 
 func (m removeModel) Init() tea.Cmd {
@@ -107,7 +108,8 @@ func (m removeModel) Init() tea.Cmd {
 func (m removeModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	switch msg := msg.(type) {
 	case string:
-		return m, tea.Sequence(tea.Println(msg), tea.Quit)
+		m.result = msg
+		return m, tea.Quit
 	default:
 		bm, cmd := m.baseModel.Update(msg)
 		m.baseModel = bm.(baseModel)
@@ -116,4 +118,11 @@ func (m removeModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 	}
 }
 
+func (m removeModel) FinalOutput() string {
+	if m.status != 0 {
+		return ""
+	}
+	return m.result
+}
+
 func (m removeModel) View() tea.View { return tea.NewView("") }

cmd/dbc/remove_test.go

@@ -0,0 +1,78 @@
+// Copyright 2026 Columnar Technologies Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"path/filepath"
+)
+
+func (suite *SubcommandTestSuite) TestRemoveOutput() {
+	m := InitCmd{Path: filepath.Join(suite.tempdir, "dbc.toml")}.GetModel()
+	suite.runCmd(m)
+
+	// Add a driver first
+	m = AddCmd{
+		Path:   filepath.Join(suite.tempdir, "dbc.toml"),
+		Driver: []string{"test-driver-1"},
+	}.GetModelCustom(
+		baseModel{getDriverRegistry: getTestDriverRegistry, downloadPkg: downloadTestPkg})
+	suite.runCmd(m)
+
+	// Remove the driver and verify output
+	m = RemoveCmd{
+		Path:   filepath.Join(suite.tempdir, "dbc.toml"),
+		Driver: "test-driver-1",
+	}.GetModelCustom(
+		baseModel{getDriverRegistry: getTestDriverRegistry, downloadPkg: downloadTestPkg})
+
+	out := suite.runCmd(m)
+	suite.Contains(out, "removed 'test-driver-1' from driver list")
+}
+
+func (suite *SubcommandTestSuite) TestRemoveNonexistentDriverError() {
+	m := InitCmd{Path: filepath.Join(suite.tempdir, "dbc.toml")}.GetModel()
+	suite.runCmd(m)
+
+	// Add a driver first so the list isn't empty
+	m = AddCmd{
+		Path:   filepath.Join(suite.tempdir, "dbc.toml"),
+		Driver: []string{"test-driver-1"},
+	}.GetModelCustom(
+		baseModel{getDriverRegistry: getTestDriverRegistry, downloadPkg: downloadTestPkg})
+	suite.runCmd(m)
+
+	// Try to remove a driver that doesn't exist
+	m = RemoveCmd{
+		Path:   filepath.Join(suite.tempdir, "dbc.toml"),
+		Driver: "nonexistent-driver",
+	}.GetModelCustom(
+		baseModel{getDriverRegistry: getTestDriverRegistry, downloadPkg: downloadTestPkg})
+
+	out := suite.runCmdErr(m)
+	suite.Contains(out, "driver 'nonexistent-driver' not found")
+}
+
+func (suite *SubcommandTestSuite) TestRemoveFromNonexistentFile() {
+	// Try to remove from a file that doesn't exist
+	m := RemoveCmd{
+		Path:   filepath.Join(suite.tempdir, "nonexistent-dbc.toml"),
+		Driver: "test-driver-1",
+	}.GetModelCustom(
+		baseModel{getDriverRegistry: getTestDriverRegistry, downloadPkg: downloadTestPkg})
+
+	out := suite.runCmdErr(m)
+	suite.Contains(out, "doesn't exist")
+	suite.Contains(out, "Did you run `dbc init`?")
+}