coder
diff --git a/‎cli/clibase/clibase.go
Lines changed: 3 additions & 0 deletions b/‎cli/clibase/clibase.go
Lines changed: 3 additions & 0 deletions
diff --git a/‎cli/clibase/clibasetest/invokation.go
Lines changed: 50 additions & 0 deletions b/‎cli/clibase/clibasetest/invokation.go
Lines changed: 50 additions & 0 deletions
@@ -5,6 +5,9 @@
 // We will extend its usage to the rest of our application, completely replacing
 // cobra/viper. It's also a candidate to be broken out into its own open-source
 // library, so we avoid deep coupling with Coder concepts.
+//
+// The Command interface is loosely based on the chi middleware pattern and
+// http.Handler/HandlerFunc.
 package clibase
 
 import (
 
@@ -0,0 +1,50 @@
+package clibasetest
+
+import (
+	"bytes"
+	"io"
+	"testing"
+
+	"github.com/coder/coder/cli/clibase"
+)
+
+// IO is the standard input, output, and error for a command.
+type IO struct {
+	Stdin  *bytes.Buffer
+	Stdout *bytes.Buffer
+	Stderr *bytes.Buffer
+}
+
+// FakeIO sets Stdin, Stdout, and Stderr to buffers.
+func FakeIO(i *clibase.Invokation) *IO {
+	b := &IO{
+		Stdin:  bytes.NewBuffer(nil),
+		Stdout: bytes.NewBuffer(nil),
+		Stderr: bytes.NewBuffer(nil),
+	}
+	i.Stdout = b.Stdout
+	i.Stderr = b.Stderr
+	i.Stdin = b.Stdin
+	return b
+}
+
+type testWriter struct {
+	prefix string
+	t      *testing.T
+}
+
+func (w *testWriter) Write(p []byte) (n int, err error) {
+	w.t.Helper()
+	w.t.Log(w.prefix, string(p))
+	return len(p), nil
+}
+
+func TestWriter(t *testing.T, prefix string) io.Writer {
+	return &testWriter{prefix: prefix, t: t}
+}
+
+// Invoke creates a fake invokation and IO.
+func Invoke(cmd *clibase.Cmd, args ...string) (*clibase.Invokation, *IO) {
+	i := cmd.Invoke(args...)
+	return i, FakeIO(i)
+}