tidy-up: drop redundant == NULL syntax

Where missed by checksrc.

Closes #21935

tests/libtest/lib1536.c

@@ -76,8 +76,7 @@ static CURLcode test_lib1536(const char *URL)
   if(!scheme || memcmp(scheme, "http", 5) != 0) {
     curl_mfprintf(stderr, "%s:%d scheme of http resource is incorrect; "
                   "expected 'http' but is %s\n",
-                  __FILE__, __LINE__,
-                  (scheme == NULL ? "NULL" : "invalid"));
+                  __FILE__, __LINE__, scheme ? "invalid" : "NULL");
     result = CURLE_HTTP_RETURNED_ERROR;
     goto test_cleanup;
   }

tests/unit/README.md

@@ -55,8 +55,8 @@ For the actual C file, here's a simple example:
 
       /* here you start doing things and checking that the results are good */
 
-      fail_unless( size == 0 , "initial size should be zero" );
-      fail_if( head == NULL , "head should not be initiated to NULL" );
+      fail_unless(size == 0, "initial size should be zero");
+      fail_if(!head, "head should not be initiated to NULL");
 
       /* you end the test code like this: */
 
@@ -87,8 +87,8 @@ Here's an example using optional initialization and cleanup:
 
       /* here you start doing things and checking that the results are good */
 
-      fail_unless( size == 0 , "initial size should be zero" );
-      fail_if( head == NULL , "head should not be initiated to NULL" );
+      fail_unless(size == 0, "initial size should be zero");
+      fail_if(!head, "head should not be initiated to NULL");
 
       /* you end the test code like this: */
 

tests/unit/unit1300.c

@@ -67,9 +67,9 @@ static CURLcode test_unit1300(const char *arg)
 
   fail_unless(Curl_llist_count(&llist) == 0,
               "list initial size should be zero");
-  fail_unless(Curl_llist_head(&llist) == NULL,
+  fail_unless(!Curl_llist_head(&llist),
               "list head should initiate to NULL");
-  fail_unless(llist_tail(&llist) == NULL,
+  fail_unless(!llist_tail(&llist),
               "list tail should initiate to NULL");
 
   /**
@@ -152,7 +152,7 @@ static CURLcode test_unit1300(const char *arg)
   fail_unless(Curl_llist_head(&llist) == element_next,
               "llist new head not modified properly");
   abort_unless(Curl_llist_head(&llist), "llist.head is NULL");
-  fail_unless(llist_node_prev(Curl_llist_head(&llist)) == NULL,
+  fail_unless(!llist_node_prev(Curl_llist_head(&llist)),
               "new head previous not set to null");
 
   /**
@@ -208,9 +208,9 @@ static CURLcode test_unit1300(const char *arg)
 
   to_remove = Curl_llist_head(&llist);
   Curl_node_remove(to_remove);
-  fail_unless(Curl_llist_head(&llist) == NULL,
+  fail_unless(!Curl_llist_head(&llist),
               "llist head is not NULL while the llist is empty");
-  fail_unless(llist_tail(&llist) == NULL,
+  fail_unless(!llist_tail(&llist),
               "llist tail is not NULL while the llist is empty");
 
   /**

tests/unit/unit1304.c

@@ -71,7 +71,7 @@ static CURLcode test_unit1304(const char *arg)
   Curl_netrc_init(&store);
   res = Curl_netrc_scan(data, &store, "test.example.com", NULL, arg, &cr_out);
   fail_unless(res == NETRC_NO_MATCH, "expected no match");
-  fail_unless(cr_out == NULL, "creds did not return NULL!");
+  fail_unless(!cr_out, "creds did not return NULL!");
   Curl_netrc_cleanup(&store);
 
   /*

tests/unit/unit1309.c

@@ -97,7 +97,7 @@ static CURLcode test_unit1309(const char *arg)
     }
   }
 
-  fail_unless(root == NULL, "tree not empty after removing all nodes");
+  fail_unless(!root, "tree not empty after removing all nodes");
 
   /* rebuild tree */
   for(i = 0; i < NUM_NODES; i++) {
@@ -127,7 +127,7 @@ static CURLcode test_unit1309(const char *arg)
     }
   }
 
-  fail_unless(root == NULL, "tree not empty when it should be");
+  fail_unless(!root, "tree not empty when it should be");
 
   UNITTEST_END_SIMPLE
 }

tests/unit/unit1605.c

@@ -53,10 +53,10 @@ static CURLcode test_unit1605(const char *arg)
   char *esc;
 
   esc = curl_easy_escape(easy, "", -1);
-  fail_unless(esc == NULL, "negative string length cannot work");
+  fail_unless(!esc, "negative string length cannot work");
 
   esc = curl_easy_unescape(easy, "%41%41%41%41", -1, &len);
-  fail_unless(esc == NULL, "negative string length cannot work");
+  fail_unless(!esc, "negative string length cannot work");
 
   UNITTEST_END(t1605_stop(easy))
 }

tests/unit/unit1620.c

@@ -127,7 +127,7 @@ static CURLcode test_unit1620(const char *arg)
 
   Curl_freeset(empty);
   for(i = (enum dupstring)0; i < STRING_LAST; i++) {
-    fail_unless(empty->set.str[i] == NULL, "Curl_free() did not set to NULL");
+    fail_unless(!empty->set.str[i], "Curl_free() did not set to NULL");
   }
 
   result = Curl_close(&dupe);

tests/unit/unit2601.c

@@ -99,9 +99,9 @@ static void check_bufq(size_t pool_spares,
 
   fail_unless(q.chunk_size == chunk_size, "chunk_size init wrong");
   fail_unless(q.max_chunks == max_chunks, "max_chunks init wrong");
-  fail_unless(q.head == NULL, "init: head not NULL");
-  fail_unless(q.tail == NULL, "init: tail not NULL");
-  fail_unless(q.spare == NULL, "init: spare not NULL");
+  fail_unless(!q.head, "init: head not NULL");
+  fail_unless(!q.tail, "init: tail not NULL");
+  fail_unless(!q.spare, "init: spare not NULL");
   fail_unless(Curl_bufq_len(&q) == 0, "init: bufq length != 0");
 
   result = Curl_bufq_write(&q, test_data, wsize, &n2);