cli/command/formatter: fix .Labels format being randomized

cli/command/formatter/container.go

@@ -68,16 +68,14 @@ ports: {{- pad .Ports 1 0}}
 
 // ContainerWrite renders the context for a list of containers
 func ContainerWrite(ctx Context, containers []container.Summary) error {
-	render := func(format func(subContext SubContext) error) error {
+	return ctx.Write(NewContainerContext(), func(format func(subContext SubContext) error) error {
 		for _, ctr := range containers {
-			err := format(&ContainerContext{trunc: ctx.Trunc, c: ctr})
-			if err != nil {
+			if err := format(&ContainerContext{trunc: ctx.Trunc, c: ctr}); err != nil {
 				return err
 			}
 		}
 		return nil
-	}
-	return ctx.Write(NewContainerContext(), render)
+	})
 }
 
 // ContainerContext is a struct used for rendering a list of containers in a Go template.
@@ -256,6 +254,7 @@ func (c *ContainerContext) Labels() string {
 	for k, v := range c.c.Labels {
 		joinLabels = append(joinLabels, k+"="+v)
 	}
+	sort.Strings(joinLabels)
 	return strings.Join(joinLabels, ",")
 }
 

cli/command/formatter/container_test.go

@@ -371,62 +371,53 @@ size: 0B
 }
 
 func TestContainerContextWriteWithNoContainers(t *testing.T) {
-	out := bytes.NewBufferString("")
-	containers := []container.Summary{}
-
 	cases := []struct {
 		context  Context
 		expected string
 	}{
 		{
 			context: Context{
 				Format: "{{.Image}}",
-				Output: out,
 			},
 		},
 		{
 			context: Context{
 				Format: "table {{.Image}}",
-				Output: out,
 			},
 			expected: "IMAGE\n",
 		},
 		{
 			context: Context{
 				Format: NewContainerFormat("{{.Image}}", false, true),
-				Output: out,
 			},
 		},
 		{
 			context: Context{
 				Format: NewContainerFormat("table {{.Image}}", false, true),
-				Output: out,
 			},
 			expected: "IMAGE\n",
 		},
 		{
 			context: Context{
 				Format: "table {{.Image}}\t{{.Size}}",
-				Output: out,
 			},
 			expected: "IMAGE     SIZE\n",
 		},
 		{
 			context: Context{
 				Format: NewContainerFormat("table {{.Image}}\t{{.Size}}", false, true),
-				Output: out,
 			},
 			expected: "IMAGE     SIZE\n",
 		},
 	}
 
 	for _, tc := range cases {
 		t.Run(string(tc.context.Format), func(t *testing.T) {
-			err := ContainerWrite(tc.context, containers)
+			out := new(bytes.Buffer)
+			tc.context.Output = out
+			err := ContainerWrite(tc.context, nil)
 			assert.NilError(t, err)
 			assert.Equal(t, out.String(), tc.expected)
-			// Clean buffer
-			out.Reset()
 		})
 	}
 }
@@ -506,28 +497,59 @@ func TestContainerContextWriteJSONField(t *testing.T) {
 }
 
 func TestContainerBackCompat(t *testing.T) {
-	containers := []container.Summary{{ID: "brewhaha"}}
-	cases := []string{
-		"ID",
-		"Names",
-		"Image",
-		"Command",
-		"CreatedAt",
-		"RunningFor",
-		"Ports",
-		"Status",
-		"Size",
-		"Labels",
-		"Mounts",
+	createdAtTime := time.Now().AddDate(-1, 0, 0) // 1 year ago
+
+	ctrContext := container.Summary{
+		ID:                      "aabbccddeeff",
+		Names:                   []string{"/foobar_baz"},
+		Image:                   "docker.io/library/ubuntu",                                                // should this have canonical format or not?
+		ImageID:                 "sha256:a5a665ff33eced1e0803148700880edab4269067ed77e27737a708d0d293fbf5", // should this have algo-prefix or not?
+		ImageManifestDescriptor: nil,
+		Command:                 "/bin/sh",
+		Created:                 createdAtTime.UTC().Unix(),
+		Ports:                   []container.Port{{PrivatePort: 8080, PublicPort: 8080, Type: "tcp"}},
+		SizeRw:                  123,
+		SizeRootFs:              12345,
+		Labels:                  map[string]string{"label1": "value1", "label2": "value2"},
+		State:                   "running",
+		Status:                  "running",
+		HostConfig: struct {
+			NetworkMode string            `json:",omitempty"`
+			Annotations map[string]string `json:",omitempty"`
+		}{
+			NetworkMode: "bridge",
+			Annotations: map[string]string{
+				"com.example.annotation": "hello",
+			},
+		},
+		NetworkSettings: nil,
+		Mounts:          nil,
 	}
-	buf := bytes.NewBuffer(nil)
-	for _, c := range cases {
-		ctx := Context{Format: Format(fmt.Sprintf("{{ .%s }}", c)), Output: buf}
-		if err := ContainerWrite(ctx, containers); err != nil {
-			t.Logf("could not render template for field '%s': %v", c, err)
-			t.Fail()
-		}
-		buf.Reset()
+
+	tests := []struct {
+		field    string
+		expected string
+	}{
+		{field: "ID", expected: "aabbccddeeff"},
+		{field: "Names", expected: "foobar_baz"},
+		{field: "Image", expected: "docker.io/library/ubuntu"},
+		{field: "Command", expected: `"/bin/sh"`},
+		{field: "CreatedAt", expected: time.Unix(createdAtTime.Unix(), 0).String()},
+		{field: "RunningFor", expected: "12 months ago"},
+		{field: "Ports", expected: "8080/tcp"},
+		{field: "Status", expected: "running"},
+		{field: "Size", expected: "123B (virtual 12.3kB)"},
+		{field: "Labels", expected: "label1=value1,label2=value2"},
+		{field: "Mounts", expected: ""},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.field, func(t *testing.T) {
+			buf := new(bytes.Buffer)
+			ctx := Context{Format: Format(fmt.Sprintf("{{ .%s }}", tc.field)), Output: buf}
+			assert.NilError(t, ContainerWrite(ctx, []container.Summary{ctrContext}))
+			assert.Check(t, is.Equal(strings.TrimSpace(buf.String()), tc.expected))
+		})
 	}
 }
 

cli/command/formatter/disk_usage.go

@@ -43,7 +43,7 @@ type DiskUsageContext struct {
 }
 
 func (ctx *DiskUsageContext) startSubsection(format string) (*template.Template, error) {
-	ctx.buffer = bytes.NewBufferString("")
+	ctx.buffer = &bytes.Buffer{}
 	ctx.header = ""
 	ctx.Format = Format(format)
 	ctx.preFormat()
@@ -87,7 +87,7 @@ func (ctx *DiskUsageContext) Write() (err error) {
 	if ctx.Verbose {
 		return ctx.verboseWrite()
 	}
-	ctx.buffer = bytes.NewBufferString("")
+	ctx.buffer = &bytes.Buffer{}
 	ctx.preFormat()
 
 	tmpl, err := ctx.parseFormat()

cli/command/formatter/formatter.go

@@ -82,6 +82,9 @@ func (c *Context) parseFormat() (*template.Template, error) {
 }
 
 func (c *Context) postFormat(tmpl *template.Template, subContext SubContext) {
+	if c.Output == nil {
+		c.Output = io.Discard
+	}
 	if c.Format.IsTable() {
 		t := tabwriter.NewWriter(c.Output, 10, 1, 3, ' ', 0)
 		buffer := bytes.NewBufferString("")
@@ -111,7 +114,7 @@ type SubFormat func(func(SubContext) error) error
 
 // Write the template to the buffer using this Context
 func (c *Context) Write(sub SubContext, f SubFormat) error {
-	c.buffer = bytes.NewBufferString("")
+	c.buffer = &bytes.Buffer{}
 	c.preFormat()
 
 	tmpl, err := c.parseFormat()

cli/command/inspect/inspector.go

@@ -26,23 +26,29 @@ type Inspector interface {
 
 // TemplateInspector uses a text template to inspect elements.
 type TemplateInspector struct {
-	outputStream io.Writer
-	buffer       *bytes.Buffer
-	tmpl         *template.Template
+	out    io.Writer
+	buffer *bytes.Buffer
+	tmpl   *template.Template
 }
 
 // NewTemplateInspector creates a new inspector with a template.
-func NewTemplateInspector(outputStream io.Writer, tmpl *template.Template) Inspector {
+func NewTemplateInspector(out io.Writer, tmpl *template.Template) *TemplateInspector {
+	if out == nil {
+		out = io.Discard
+	}
 	return &TemplateInspector{
-		outputStream: outputStream,
-		buffer:       new(bytes.Buffer),
-		tmpl:         tmpl,
+		out:    out,
+		buffer: new(bytes.Buffer),
+		tmpl:   tmpl,
 	}
 }
 
 // NewTemplateInspectorFromString creates a new TemplateInspector from a string
 // which is compiled into a template.
 func NewTemplateInspectorFromString(out io.Writer, tmplStr string) (Inspector, error) {
+	if out == nil {
+		return nil, errors.New("no output stream")
+	}
 	if tmplStr == "" {
 		return NewIndentedInspector(out), nil
 	}
@@ -65,6 +71,9 @@ type GetRefFunc func(ref string) (any, []byte, error)
 // Inspect fetches objects by reference using GetRefFunc and writes the json
 // representation to the output writer.
 func Inspect(out io.Writer, references []string, tmplStr string, getRef GetRefFunc) error {
+	if out == nil {
+		return errors.New("no output stream")
+	}
 	inspector, err := NewTemplateInspectorFromString(out, tmplStr)
 	if err != nil {
 		return cli.StatusError{StatusCode: 64, Status: err.Error()}
@@ -138,18 +147,21 @@ func (i *TemplateInspector) tryRawInspectFallback(rawElement []byte) error {
 // Flush writes the result of inspecting all elements into the output stream.
 func (i *TemplateInspector) Flush() error {
 	if i.buffer.Len() == 0 {
-		_, err := io.WriteString(i.outputStream, "\n")
+		_, err := io.WriteString(i.out, "\n")
 		return err
 	}
-	_, err := io.Copy(i.outputStream, i.buffer)
+	_, err := io.Copy(i.out, i.buffer)
 	return err
 }
 
 // NewIndentedInspector generates a new inspector with an indented representation
 // of elements.
-func NewIndentedInspector(outputStream io.Writer) Inspector {
-	return &elementsInspector{
-		outputStream: outputStream,
+func NewIndentedInspector(out io.Writer) Inspector {
+	if out == nil {
+		out = io.Discard
+	}
+	return &jsonInspector{
+		out: out,
 		raw: func(dst *bytes.Buffer, src []byte) error {
 			return json.Indent(dst, src, "", "    ")
 		},
@@ -161,23 +173,26 @@ func NewIndentedInspector(outputStream io.Writer) Inspector {
 
 // NewJSONInspector generates a new inspector with a compact representation
 // of elements.
-func NewJSONInspector(outputStream io.Writer) Inspector {
-	return &elementsInspector{
-		outputStream: outputStream,
-		raw:          json.Compact,
-		el:           json.Marshal,
+func NewJSONInspector(out io.Writer) Inspector {
+	if out == nil {
+		out = io.Discard
+	}
+	return &jsonInspector{
+		out: out,
+		raw: json.Compact,
+		el:  json.Marshal,
 	}
 }
 
-type elementsInspector struct {
-	outputStream io.Writer
-	elements     []any
-	rawElements  [][]byte
-	raw          func(dst *bytes.Buffer, src []byte) error
-	el           func(v any) ([]byte, error)
+type jsonInspector struct {
+	out         io.Writer
+	elements    []any
+	rawElements [][]byte
+	raw         func(dst *bytes.Buffer, src []byte) error
+	el          func(v any) ([]byte, error)
 }
 
-func (e *elementsInspector) Inspect(typedElement any, rawElement []byte) error {
+func (e *jsonInspector) Inspect(typedElement any, rawElement []byte) error {
 	if rawElement != nil {
 		e.rawElements = append(e.rawElements, rawElement)
 	} else {
@@ -186,9 +201,9 @@ func (e *elementsInspector) Inspect(typedElement any, rawElement []byte) error {
 	return nil
 }
 
-func (e *elementsInspector) Flush() error {
+func (e *jsonInspector) Flush() error {
 	if len(e.elements) == 0 && len(e.rawElements) == 0 {
-		_, err := io.WriteString(e.outputStream, "[]\n")
+		_, err := io.WriteString(e.out, "[]\n")
 		return err
 	}
 
@@ -216,9 +231,9 @@ func (e *elementsInspector) Flush() error {
 		buffer = bytes.NewReader(b)
 	}
 
-	if _, err := io.Copy(e.outputStream, buffer); err != nil {
+	if _, err := io.Copy(e.out, buffer); err != nil {
 		return err
 	}
-	_, err := io.WriteString(e.outputStream, "\n")
+	_, err := io.WriteString(e.out, "\n")
 	return err
 }