Update simple test case to merge an instance.

Author: peterhuene

crates/wac-graph/tests/graphs/simple/bar.wat

@@ -1,6 +1,8 @@
 (component
   (import "e" (func))
   (import "i2" (instance))
-  (import "merged" (instance))
+  (import "merged" (instance
+    (export "a" (func))
+  ))
   (export "e" (func 0))
 )

crates/wac-graph/tests/graphs/simple/encoded.wat

@@ -4,7 +4,12 @@
   )
   (import "i1" (instance (;0;) (type 0)))
   (type (;1;)
-    (instance)
+    (instance
+      (type (;0;) (func))
+      (export (;0;) "a" (func (type 0)))
+      (type (;1;) (func))
+      (export (;1;) "b" (func (type 1)))
+    )
   )
   (import "merged" (instance (;1;) (type 1)))
   (type (;2;)
@@ -22,7 +27,12 @@
     )
     (import "i1" (instance (;0;) (type 2)))
     (type (;3;)
-      (instance)
+      (instance
+        (type (;0;) (func))
+        (export (;0;) "a" (func (type 0)))
+        (type (;1;) (func))
+        (export (;1;) "b" (func (type 1)))
+      )
     )
     (import "merged" (instance (;1;) (type 3)))
     (export (;1;) "bar" (func 0))
@@ -43,7 +53,10 @@
     )
     (import "i2" (instance (;0;) (type 1)))
     (type (;2;)
-      (instance)
+      (instance
+        (type (;0;) (func))
+        (export (;0;) "a" (func (type 0)))
+      )
     )
     (import "merged" (instance (;1;) (type 2)))
     (export (;1;) "e" (func 0))

crates/wac-graph/tests/graphs/simple/foo.wat

@@ -2,6 +2,9 @@
   (type (export "f") (func))
   (import "foo" (func))
   (import "i1" (instance))
-  (import "merged" (instance))
+  (import "merged" (instance
+      (export "a" (func))
+      (export "b" (func))
+  ))
   (export "bar" (func 0))
 )