Interpolate strings in curly braces with a map.

interpolate.go

package util

import "strings"

// Interpolate replaces the values in the input string
// inside parentheses with the params supplied.
// Example:
//		Interpolate("/{owner}/{repo}", map[string]string{"owner: "golang", "repo": "go"})
// Returns:
//		"/golang/go"
func Interpolate(str string, values map[string]string) string {
	formattedStr := str

	for k, v := range values {
		t := "{" + k + "}"

		formattedStr = strings.Replace(formattedStr, t, v, -1)
	}

	return formattedStr
}

interpolate_test.go

package util

import (
	"testing"

	"github.com/magiconair/properties/assert"
)

func TestInterpolate(t *testing.T) {
	tt := []struct {
		name     string
		str      string
		expected string
		val      map[string]string
	}{
		{
			"Should interpolate the value",
			"Hello {adjective} world",
			"Hello cruel world",
			map[string]string{
				"adjective": "cruel",
			},
		},
		{
			"Should interpolate multiple values",
			"/{owner}/{repo}/",
			"/golang/go/",
			map[string]string{
				"owner": "golang",
				"repo":  "go",
			},
		},
		{
			"Should ignore all absent values",
			"Hello {adjective} world {punctuation}",
			"Hello cruel world {punctuation}",
			map[string]string{
				"adjective": "cruel",
			},
		},
	}

	for _, test := range tt {
		t.Run(test.name, func(t *testing.T) {
			formattedStr := Interpolate(test.str, test.val)

			assert.Equal(t, formattedStr, test.expected)
		})
	}
}