make environment variable interpolation preprocessor optional (#1715)

config/reader/json/json_test.go

@@ -3,6 +3,7 @@ package json
 import (
 	"testing"
 
+	"github.com/micro/go-micro/v2/config/reader"
 	"github.com/micro/go-micro/v2/config/source"
 )
 
@@ -23,7 +24,46 @@ func TestReader(t *testing.T) {
 		},
 	}
 
-	r := NewReader()
+	values := newTestValues(t, data)
+
+	for _, test := range testData {
+		if v := values.Get(test.path...).String(""); v != test.value {
+			t.Fatalf("Expected %s got %s for path %v", test.value, v, test.path)
+		}
+	}
+}
+
+func TestDisableReplaceEnvVars(t *testing.T) {
+	data := []byte(`{"foo": "bar", "baz": {"bar": "test/${test}"}}`)
+
+	tests := []struct {
+		path  []string
+		value string
+		opts  []reader.Option
+	}{
+		{
+			[]string{"baz", "bar"},
+			"test/",
+			nil,
+		},
+		{
+			[]string{"baz", "bar"},
+			"test/${test}",
+			[]reader.Option{reader.WithDisableReplaceEnvVars()},
+		},
+	}
+
+	for _, test := range tests {
+		values := newTestValues(t, data, test.opts...)
+
+		if v := values.Get(test.path...).String(""); v != test.value {
+			t.Fatalf("Expected %s got %s for path %v", test.value, v, test.path)
+		}
+	}
+}
+
+func newTestValues(t *testing.T, data []byte, opts ...reader.Option) reader.Values {
+	r := NewReader(opts...)
 
 	c, err := r.Merge(&source.ChangeSet{Data: data}, &source.ChangeSet{})
 	if err != nil {
@@ -35,9 +75,5 @@ func TestReader(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	for _, test := range testData {
-		if v := values.Get(test.path...).String(""); v != test.value {
-			t.Fatalf("Expected %s got %s for path %v", test.value, v, test.path)
-		}
-	}
+	return values
 }