Index: src/expr.c
==================================================================
--- src/expr.c
+++ src/expr.c
@@ -3657,10 +3657,26 @@
       */
       if( pDef->funcFlags & SQLITE_FUNC_UNLIKELY ){
         assert( nFarg>=1 );
         return sqlite3ExprCodeTarget(pParse, pFarg->a[0].pExpr, target);
       }
+
+#ifdef SQLITE_DEBUG
+      /* The AFFINITY() function evaluates to a string that describes
+      ** the type affinity of the argument.  This is used for testing of
+      ** the SQLite type logic.
+      */
+      if( pDef->funcFlags & SQLITE_FUNC_AFFINITY ){
+        const char *azAff[] = { "blob", "text", "numeric", "integer", "real" };
+        char aff;
+        assert( nFarg==1 );
+        aff = sqlite3ExprAffinity(pFarg->a[0].pExpr);
+        sqlite3VdbeLoadString(v, target, 
+                              aff ? azAff[aff-SQLITE_AFF_BLOB] : "none");
+        return target;
+      }
+#endif
 
       for(i=0; i<nFarg; i++){
         if( i<32 && sqlite3ExprIsConstant(pFarg->a[i].pExpr) ){
           testcase( i==31 );
           constMask |= MASKBIT32(i);

Index: src/func.c
==================================================================
--- src/func.c
+++ src/func.c
@@ -1773,10 +1773,13 @@
     DFUNCTION(sqlite_compileoption_get, 1, 0, 0, compileoptiongetFunc  ),
 #endif /* SQLITE_OMIT_COMPILEOPTION_DIAGS */
     FUNCTION2(unlikely,          1, 0, 0, noopFunc,  SQLITE_FUNC_UNLIKELY),
     FUNCTION2(likelihood,        2, 0, 0, noopFunc,  SQLITE_FUNC_UNLIKELY),
     FUNCTION2(likely,            1, 0, 0, noopFunc,  SQLITE_FUNC_UNLIKELY),
+#ifdef SQLITE_DEBUG
+    FUNCTION2(affinity,          1, 0, 0, noopFunc,  SQLITE_FUNC_AFFINITY),
+#endif
     FUNCTION(ltrim,              1, 1, 0, trimFunc         ),
     FUNCTION(ltrim,              2, 1, 0, trimFunc         ),
     FUNCTION(rtrim,              1, 2, 0, trimFunc         ),
     FUNCTION(rtrim,              2, 2, 0, trimFunc         ),
     FUNCTION(trim,               1, 3, 0, trimFunc         ),

Index: src/sqliteInt.h
==================================================================
--- src/sqliteInt.h
+++ src/sqliteInt.h
@@ -1563,10 +1563,11 @@
 #define SQLITE_FUNC_UNLIKELY 0x0400 /* Built-in unlikely() function */
 #define SQLITE_FUNC_CONSTANT 0x0800 /* Constant inputs give a constant output */
 #define SQLITE_FUNC_MINMAX   0x1000 /* True for min() and max() aggregates */
 #define SQLITE_FUNC_SLOCHNG  0x2000 /* "Slow Change". Value constant during a
                                     ** single query - might change over time */
+#define SQLITE_FUNC_AFFINITY 0x4000 /* Built-in affinity() function */
 
 /*
 ** The following three macros, FUNCTION(), LIKEFUNC() and AGGREGATE() are
 ** used to create the initializers for the FuncDef structures.
 **