jq: add option to pretty print JSON output

Adds a new function `EvaluateFormatted` to maintain backward compatibility.
Indenting output by 2 spaces matches jq output.

pkg/jq/jq.go

@@ -14,6 +14,12 @@ import (
 
 // Evaluate a jq expression against an input and write it to an output.
 func Evaluate(input io.Reader, output io.Writer, expr string) error {
+	return EvaluateFormatted(input, output, expr, false)
+}
+
+// Evaluate a jq expression against an input and write it to an output, either without
+// whitespace or with 2 spaces of indentation per level (pretty printed).
+func EvaluateFormatted(input io.Reader, output io.Writer, expr string, pretty_print bool) error {
 	query, err := gojq.Parse(expr)
 	if err != nil {
 		return err
@@ -40,6 +46,9 @@ func Evaluate(input io.Reader, output io.Writer, expr string) error {
 	}
 
 	enc := json.NewEncoder(output)
+	if pretty_print {
+		enc.SetIndent("", "  ") // pretty print, jq style
+	}
 
 	iter := code.Run(responseData)
 	for {

pkg/jq/jq_test.go

@@ -10,11 +10,12 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func TestEvaluate(t *testing.T) {
+func TestEvaluateFormatted(t *testing.T) {
 	t.Setenv("CODE", "code_c")
 	type args struct {
-		json io.Reader
-		expr string
+		json         io.Reader
+		expr         string
+		pretty_print bool
 	}
 	tests := []struct {
 		name    string
@@ -25,40 +26,54 @@ func TestEvaluate(t *testing.T) {
 		{
 			name: "simple",
 			args: args{
-				json: strings.NewReader(`{"name":"Mona", "arms":8}`),
-				expr: `.name`,
+				json:         strings.NewReader(`{"name":"Mona", "arms":8}`),
+				expr:         `.name`,
+				pretty_print: false,
 			},
 			wantW: "Mona\n",
 		},
 		{
 			name: "multiple queries",
 			args: args{
-				json: strings.NewReader(`{"name":"Mona", "arms":8}`),
-				expr: `.name,.arms`,
+				json:         strings.NewReader(`{"name":"Mona", "arms":8}`),
+				expr:         `.name,.arms`,
+				pretty_print: false,
 			},
 			wantW: "Mona\n8\n",
 		},
 		{
 			name: "object as JSON",
 			args: args{
-				json: strings.NewReader(`{"user":{"login":"monalisa"}}`),
-				expr: `.user`,
+				json:         strings.NewReader(`{"user":{"login":"monalisa"}}`),
+				expr:         `.user`,
+				pretty_print: false,
 			},
 			wantW: "{\"login\":\"monalisa\"}\n",
 		},
+		{
+			name: "object as JSON, pretty printed",
+			args: args{
+				json:         strings.NewReader(`{"user":{"login":"monalisa"}}`),
+				expr:         `.user`,
+				pretty_print: true,
+			},
+			wantW: "{\n  \"login\": \"monalisa\"\n}\n",
+		},
 		{
 			name: "empty array",
 			args: args{
-				json: strings.NewReader(`[]`),
-				expr: `.`,
+				json:         strings.NewReader(`[]`),
+				expr:         `.`,
+				pretty_print: false,
 			},
 			wantW: "[]\n",
 		},
 		{
 			name: "empty array 2",
 			args: args{
-				json: strings.NewReader(`[]`),
-				expr: `[]`,
+				json:         strings.NewReader(`[]`),
+				expr:         `[]`,
+				pretty_print: false,
 			},
 			wantW: "[]\n",
 		},
@@ -79,7 +94,8 @@ func TestEvaluate(t *testing.T) {
 						"labels": [{}, {"name":"feature"}]
 					}
 				]`)),
-				expr: `.[] | [.title,(.labels | map(.name) | join(","))] | @tsv`,
+				expr:         `.[] | [.title,(.labels | map(.name) | join(","))] | @tsv`,
+				pretty_print: false,
 			},
 			wantW: heredoc.Doc(`
 				First title	bug,help wanted
@@ -104,15 +120,16 @@ func TestEvaluate(t *testing.T) {
 						"labels": [{}, {"name":"feature"}]
 					}
 				]`)),
-				expr: `.[] | select(.title == env.CODE) | .labels`,
+				expr:         `.[] | select(.title == env.CODE) | .labels`,
+				pretty_print: true,
 			},
-			wantW: "[{},{\"name\":\"feature\"}]\n",
+			wantW: "[\n  {},\n  {\n    \"name\": \"feature\"\n  }\n]\n",
 		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			w := &bytes.Buffer{}
-			err := Evaluate(tt.args.json, w, tt.args.expr)
+			err := EvaluateFormatted(tt.args.json, w, tt.args.expr, tt.args.pretty_print)
 			if tt.wantErr {
 				assert.Error(t, err)
 				return