Change the string literal for the body of MultiHTTP requests into an …

…expression that interpolates referenced variables.

internal/prober/multihttp/script.go

@@ -3,7 +3,6 @@ package multihttp
 import (
 	"bytes"
 	"embed"
-	"encoding/base64"
 	"fmt"
 	"regexp"
 	"strings"
@@ -96,11 +95,8 @@ func buildBody(body *sm.HttpRequestBody) string {
 
 	default:
 		var buf strings.Builder
-
-		buf.WriteString(`encoding.b64decode("`)
-		buf.WriteString(base64.RawStdEncoding.EncodeToString(body.Payload))
-		buf.WriteString(`", 'rawstd', "b")`)
-
+		bodyString := string(body.Payload)
+		buf.WriteString(performVariableExpansion(bodyString))
 		return buf.String()
 	}
 }

internal/prober/multihttp/script_test.go

@@ -320,9 +320,17 @@ func TestBuildBody(t *testing.T) {
 		input    input
 		expected string
 	}{
+		"variable in body is interpolated correctly": {
+			input:    input{body: &sm.HttpRequestBody{Payload: []byte("test ${testVar} works")}},
+			expected: "'test '+vars['testVar']+' works'", // 'test '+vars['testVar']+' works'
+		},
+		"body starting with variable is interpolated correctly": {
+			input:    input{body: &sm.HttpRequestBody{Payload: []byte("${testVar} test")}},
+			expected: "vars['testVar']+' test'", // vars['testVar']+' test'
+		},
 		"not empty": {
 			input:    input{body: &sm.HttpRequestBody{Payload: []byte("test")}},
-			expected: `encoding.b64decode("dGVzdA", 'rawstd', "b")`,
+			expected: "'test'", // 'test'
 		},
 		"nil": {
 			input:    input{body: nil},