replacer: code refactor

Signed-off-by: Tw <tw19881113@gmail.com>

caddyhttp/httpserver/replacer_test.go

@@ -24,28 +24,12 @@ func TestNewReplacer(t *testing.T) {
 
 	switch v := rep.(type) {
 	case *replacer:
-		if v.replacements["{host}"]() != "localhost" {
+		if v.getSubstitution("{host}") != "localhost" {
 			t.Error("Expected host to be localhost")
 		}
-		if v.replacements["{method}"]() != "POST" {
+		if v.getSubstitution("{method}") != "POST" {
 			t.Error("Expected request method  to be POST")
 		}
-
-		// Response placeholders should only be set after call to Replace()
-		got, want := "", ""
-		if getReplacement, ok := v.replacements["{status}"]; ok {
-			got = getReplacement()
-		}
-		if want := ""; got != want {
-			t.Errorf("Expected status to NOT be set before Replace() is called; was: %s", got)
-		}
-		rep.Replace("{foobar}")
-		if getReplacement, ok := v.replacements["{status}"]; ok {
-			got = getReplacement()
-		}
-		if want = "200"; got != want {
-			t.Errorf("Expected status to be %s, was: %s", want, got)
-		}
 	default:
 		t.Fatalf("Expected *replacer underlying Replacer type, got: %#v", rep)
 	}
@@ -94,19 +78,21 @@ func TestReplace(t *testing.T) {
 
 	complexCases := []struct {
 		template     string
-		replacements map[string]func() string
+		replacements map[string]string
 		expect       string
 	}{
-		{"/a{1}/{2}",
-			map[string]func() string{
-				"{1}": func() string { return "12" },
-				"{2}": func() string { return "" }},
+		{
+			"/a{1}/{2}",
+			map[string]string{
+				"{1}": "12",
+				"{2}": "",
+			},
 			"/a12/"},
 	}
 
 	for _, c := range complexCases {
 		repl := &replacer{
-			replacements: c.replacements,
+			customReplacements: c.replacements,
 		}
 		if expected, actual := c.expect, repl.Replace(c.template); expected != actual {
 			t.Errorf("for template '%s', expected '%s', got '%s'", c.template, expected, actual)