Use cljr--resolve-alias to double check before inserting require

Attempted to add tests using `cljr--in-namespace-declaration`, but that method
appears to always return nil, and isn't actually working. Left that be on the
other non `cljr-magic-require-prompts-include-context` path to avoid changes in
behavior.

Given current behavior this test is not strictly necessary on the prompting
path, as candidates with existing references should already be filtered out.
Leaving it for now to keep the behavior close to before. Also, there is the
possibility that the `cljr--magic-prompt-or-select-namespace` could allow users
to type in a custom libspec at the prompt, in which case we would still need to
filter to ensure it was not a duplicate.

Added some test coverage to `cljr--resolve-alias`.

clj-refactor.el

@@ -2149,10 +2149,8 @@ will add the corresponding require statement to the ns form."
     (if cljr-magic-require-prompts-includes-context
         (when-let (selection (cljr--magic-prompt-or-select-namespace
                               (cljr--magic-require-candidates alias-ref)))
-          (let ((alias (symbol-name (cl-first selection)))
-                (namespace (cl-second selection)))
-            (when (and (not (cljr--in-namespace-declaration-p (concat ":as " alias "\b")))
-                       (not (cljr--in-namespace-declaration-p (concat ":as-alias " alias "\b"))))
+          (cl-destructuring-bind (alias namespace _) selection
+            (unless (cljr--resolve-alias (symbol-name alias))
               (cljr--insert-require-libspec (format "[%s :as %s]" namespace alias)))))
       (when-let (aliases (cljr--magic-requires-lookup-alias alias-ref))
         (let ((short (cl-first aliases))

tests/unit-test.el

@@ -174,6 +174,24 @@
       (expect (cljr--magic-prompt-or-select-namespace '((a b.a (:clj))))
               :to-equal '(a b.a (:clj))))))
 
+(defun cljr--test-resolve (alias)
+  (cljr--with-clojure-temp-file "foo.clj"
+    (insert "(ns foo (:require [a.a :as a] [a.b :as-alias b] [a.b.c :as b.c]))")
+    (cljr--resolve-alias alias)))
+
+(describe "cljr--resolve-alias"
+  (it "returns nil on no matching alias"
+    (expect (cljr--test-resolve "missing") :to-be nil))
+
+  (it "finds alias :as `a'"
+    (expect (cljr--test-resolve "a") :to-equal "a.a"))
+
+  (it "finds alias :as-alias `b'"
+    (expect (cljr--test-resolve "b") :to-equal "a.b"))
+
+  (it "finds dotted alias `b.c'"
+    (expect (cljr--test-resolve "b.c") :to-equal "a.b.c")))
+
 (describe "cljr-slash"
   (describe "with prompts including context"
     (before-each (setq cljr-magic-require-prompts-includes-context t))