feat: show banner when workspace is outdated (#4926)

* feat: show banner when workspace is outdated

* Address PR comments

* Fix: writer

cli/ssh_internal_test.go

@@ -0,0 +1,58 @@
+package cli
+
+import (
+	"net/url"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/coder/coder/codersdk"
+)
+
+const (
+	fakeOwnerName     = "fake-owner-name"
+	fakeServerURL     = "https://fake-foo-url"
+	fakeWorkspaceName = "fake-workspace-name"
+)
+
+func TestVerifyWorkspaceOutdated(t *testing.T) {
+	t.Parallel()
+
+	serverURL, err := url.Parse(fakeServerURL)
+	require.NoError(t, err)
+
+	client := codersdk.Client{URL: serverURL}
+
+	t.Run("Up-to-date", func(t *testing.T) {
+		t.Parallel()
+
+		workspace := codersdk.Workspace{Name: fakeWorkspaceName, OwnerName: fakeOwnerName}
+
+		_, outdated := verifyWorkspaceOutdated(&client, workspace)
+
+		assert.False(t, outdated, "workspace should be up-to-date")
+	})
+	t.Run("Outdated", func(t *testing.T) {
+		t.Parallel()
+
+		workspace := codersdk.Workspace{Name: fakeWorkspaceName, OwnerName: fakeOwnerName, Outdated: true}
+
+		updateWorkspaceBanner, outdated := verifyWorkspaceOutdated(&client, workspace)
+
+		assert.True(t, outdated, "workspace should be outdated")
+		assert.NotEmpty(t, updateWorkspaceBanner, "workspace banner should be present")
+	})
+}
+
+func TestBuildWorkspaceLink(t *testing.T) {
+	t.Parallel()
+
+	serverURL, err := url.Parse(fakeServerURL)
+	require.NoError(t, err)
+
+	workspace := codersdk.Workspace{Name: fakeWorkspaceName, OwnerName: fakeOwnerName}
+	workspaceLink := buildWorkspaceLink(serverURL, workspace)
+
+	assert.Equal(t, workspaceLink.String(), fakeServerURL+"/@"+fakeOwnerName+"/"+fakeWorkspaceName)
+}