Merge consecutive text nodes when inspecting markdown (#9112)

* Fix assertion order

expected/actual were in wrong order, resulting in misleading output in
case of failing tests

* Merge consesutive markdown text nodes

This ensures that parser quirks such as "hello!" being parsed as
two separate nodes ("hello" and "!") are not exposed to code inspecting
a markdown strings.

utils/markdown/inspect.go

@@ -13,7 +13,7 @@ func Inspect(markdown string, f func(interface{}) bool) {
 		}
 		switch v := block.(type) {
 		case *Paragraph:
-			for _, inline := range v.ParseInlines(referenceDefinitions) {
+			for _, inline := range MergeInlineText(v.ParseInlines(referenceDefinitions)) {
 				InspectInline(inline, func(inline Inline) bool {
 					return f(inline)
 				})