caddyfile: tighten makeArgsReplacer empty/nil tests

Neither test asserted a real outcome (one compared against an
unreachable literal, the other logged then discarded the result).
Since Replacer.ReplaceAll substitutes the provided default for
unknown placeholders, both cases can be checked with deterministic
equality.

Signed-off-by: Mohammed Al Sahaf <msaa1990@gmail.com>

caddyconfig/caddyfile/importargs_test.go

@@ -252,21 +252,17 @@ func TestMakeArgsReplacer(t *testing.T) {
 func TestMakeArgsReplacerEmpty(t *testing.T) {
 	repl := makeArgsReplacer([]string{})
 
-	// With no args, any index should be out of bounds
 	got := repl.ReplaceAll("{args[0]}", "")
-	if got == "something" {
-		t.Errorf("repl.ReplaceAll with empty args should not produce a value, got %q", got)
+	if got != "" {
+		t.Errorf("repl.ReplaceAll({args[0]}, \"\") with empty args = %q, want \"\"", got)
 	}
 }
 
 func TestMakeArgsReplacerNil(t *testing.T) {
 	repl := makeArgsReplacer(nil)
 
-	// Should not panic with nil args
 	got := repl.ReplaceAll("{args[0]}", "DEFAULT")
-	if got == "" {
-		// The replacer returns the default when unmatched
-		t.Log("nil args: correctly returned empty/default for {args[0]}")
+	if got != "DEFAULT" {
+		t.Errorf("repl.ReplaceAll({args[0]}, \"DEFAULT\") with nil args = %q, want \"DEFAULT\"", got)
 	}
-	_ = got
 }