Improve coverage and fix an off-by-one

src/fellow_cache.c

@@ -2045,7 +2045,7 @@ fellow_busy_obj_alloc(struct fellow_cache *fc,
 
 //	DBG("roundup fdo + fdsl dsk_sz %zu", dsk_sz);
 
-	assert(dsk_sz > asz);
+	assert(dsk_sz >= asz);
 	sz = ((dsk_sz - asz) + sizeof(struct fellow_disk_seg))
 	    / sizeof(struct fellow_disk_seg);
 	assert(sz <= FELLOW_DISK_SEGLIST_MAX_SEGS);
@@ -5963,12 +5963,13 @@ t_cache(unsigned chksum)
 
 	t_lcb(fc);
 
-	// === empty obj
-	fbo = fellow_busy_obj_alloc(fc, &fco, &priv2, 1234).r.ptr;
-	CHECK_OBJ_NOTNULL(fbo, FELLOW_BUSY_MAGIC);
-
-	test_bocdone(fbo, TRUST_ME(hash), 1);
-	fellow_cache_obj_deref(fc, fco);
+	// === empty obj, loop sizes
+	for (sz = 0; sz < 4096 ; sz += 8) {
+		fbo = fellow_busy_obj_alloc(fc, &fco, &priv2, sz).r.ptr;
+		CHECK_OBJ_NOTNULL(fbo, FELLOW_BUSY_MAGIC);
+		test_bocdone(fbo, TRUST_ME(hash), 1);
+		fellow_cache_obj_deref(fc, fco);
+	}
 
 	// === max out region alloc
 	fbo = fellow_busy_obj_alloc(fc, &fco, &priv2, 1234).r.ptr;