diff --git a/test/include/test/extent_hooks.h b/test/include/test/extent_hooks.h
new file mode 100644
index 00000000..f50747d0
--- /dev/null
+++ b/test/include/test/extent_hooks.h
@@ -0,0 +1,264 @@
+/*
+ * Boilerplate code used for testing extent hooks via interception and
+ * passthrough.
+ */
+
+static void	*extent_alloc_hook(extent_hooks_t *extent_hooks, void *new_addr,
+    size_t size, size_t alignment, bool *zero, bool *commit,
+    unsigned arena_ind);
+static bool	extent_dalloc_hook(extent_hooks_t *extent_hooks, void *addr,
+    size_t size, bool committed, unsigned arena_ind);
+static bool	extent_commit_hook(extent_hooks_t *extent_hooks, void *addr,
+    size_t size, size_t offset, size_t length, unsigned arena_ind);
+static bool	extent_decommit_hook(extent_hooks_t *extent_hooks, void *addr,
+    size_t size, size_t offset, size_t length, unsigned arena_ind);
+static bool	extent_purge_lazy_hook(extent_hooks_t *extent_hooks, void *addr,
+    size_t size, size_t offset, size_t length, unsigned arena_ind);
+static bool	extent_purge_forced_hook(extent_hooks_t *extent_hooks,
+    void *addr, size_t size, size_t offset, size_t length, unsigned arena_ind);
+static bool	extent_split_hook(extent_hooks_t *extent_hooks, void *addr,
+    size_t size, size_t size_a, size_t size_b, bool committed,
+    unsigned arena_ind);
+static bool	extent_merge_hook(extent_hooks_t *extent_hooks, void *addr_a,
+    size_t size_a, void *addr_b, size_t size_b, bool committed,
+    unsigned arena_ind);
+
+static extent_hooks_t *default_hooks;
+static extent_hooks_t hooks = {
+	extent_alloc_hook,
+	extent_dalloc_hook,
+	extent_commit_hook,
+	extent_decommit_hook,
+	extent_purge_lazy_hook,
+	extent_purge_forced_hook,
+	extent_split_hook,
+	extent_merge_hook
+};
+
+/* Control whether hook functions pass calls through to default hooks. */
+static bool try_alloc = true;
+static bool try_dalloc = true;
+static bool try_commit = true;
+static bool try_decommit = true;
+static bool try_purge_lazy = true;
+static bool try_purge_forced = true;
+static bool try_split = true;
+static bool try_merge = true;
+
+/* Set to false prior to operations, then introspect after operations. */
+static bool called_alloc;
+static bool called_dalloc;
+static bool called_commit;
+static bool called_decommit;
+static bool called_purge_lazy;
+static bool called_purge_forced;
+static bool called_split;
+static bool called_merge;
+
+/* Set to false prior to operations, then introspect after operations. */
+static bool did_alloc;
+static bool did_dalloc;
+static bool did_commit;
+static bool did_decommit;
+static bool did_purge_lazy;
+static bool did_purge_forced;
+static bool did_split;
+static bool did_merge;
+
+#if 0
+#  define TRACE_HOOK(fmt, ...) malloc_printf(fmt, __VA_ARGS__)
+#else
+#  define TRACE_HOOK(fmt, ...)
+#endif
+
+static void *
+extent_alloc_hook(extent_hooks_t *extent_hooks, void *new_addr, size_t size,
+    size_t alignment, bool *zero, bool *commit, unsigned arena_ind)
+{
+	void *ret;
+
+	TRACE_HOOK("%s(extent_hooks=%p, new_addr=%p, size=%zu, alignment=%zu, "
+	    "*zero=%s, *commit=%s, arena_ind=%u)\n", __func__, extent_hooks,
+	    new_addr, size, alignment, *zero ?  "true" : "false", *commit ?
+	    "true" : "false", arena_ind);
+	assert_ptr_eq(extent_hooks, &hooks,
+	    "extent_hooks should be same as pointer used to set hooks");
+	assert_ptr_eq(extent_hooks->alloc, extent_alloc_hook,
+	    "Wrong hook function");
+	called_alloc = true;
+	if (!try_alloc)
+		return (NULL);
+	ret = default_hooks->alloc(default_hooks, new_addr, size, alignment,
+	    zero, commit, 0);
+	did_alloc = (ret != NULL);
+	return (ret);
+}
+
+static bool
+extent_dalloc_hook(extent_hooks_t *extent_hooks, void *addr, size_t size,
+    bool committed, unsigned arena_ind)
+{
+	bool err;
+
+	TRACE_HOOK("%s(extent_hooks=%p, addr=%p, size=%zu, committed=%s, "
+	    "arena_ind=%u)\n", __func__, extent_hooks, addr, size, committed ?
+	    "true" : "false", arena_ind);
+	assert_ptr_eq(extent_hooks, &hooks,
+	    "extent_hooks should be same as pointer used to set hooks");
+	assert_ptr_eq(extent_hooks->dalloc, extent_dalloc_hook,
+	    "Wrong hook function");
+	called_dalloc = true;
+	if (!try_dalloc)
+		return (true);
+	err = default_hooks->dalloc(default_hooks, addr, size, committed, 0);
+	did_dalloc = !err;
+	return (err);
+}
+
+static bool
+extent_commit_hook(extent_hooks_t *extent_hooks, void *addr, size_t size,
+    size_t offset, size_t length, unsigned arena_ind)
+{
+	bool err;
+
+	TRACE_HOOK("%s(extent_hooks=%p, addr=%p, size=%zu, offset=%zu, "
+	    "length=%zu, arena_ind=%u)\n", __func__, extent_hooks, addr, size,
+	    offset, length, arena_ind);
+	assert_ptr_eq(extent_hooks, &hooks,
+	    "extent_hooks should be same as pointer used to set hooks");
+	assert_ptr_eq(extent_hooks->commit, extent_commit_hook,
+	    "Wrong hook function");
+	called_commit = true;
+	if (!try_commit)
+		return (true);
+	err = default_hooks->commit(default_hooks, addr, size, offset, length,
+	    0);
+	did_commit = !err;
+	return (err);
+}
+
+static bool
+extent_decommit_hook(extent_hooks_t *extent_hooks, void *addr, size_t size,
+    size_t offset, size_t length, unsigned arena_ind)
+{
+	bool err;
+
+	TRACE_HOOK("%s(extent_hooks=%p, addr=%p, size=%zu, offset=%zu, "
+	    "length=%zu, arena_ind=%u)\n", __func__, extent_hooks, addr, size,
+	    offset, length, arena_ind);
+	assert_ptr_eq(extent_hooks, &hooks,
+	    "extent_hooks should be same as pointer used to set hooks");
+	assert_ptr_eq(extent_hooks->decommit, extent_decommit_hook,
+	    "Wrong hook function");
+	called_decommit = true;
+	if (!try_decommit)
+		return (true);
+	err = default_hooks->decommit(default_hooks, addr, size, offset, length,
+	    0);
+	did_decommit = !err;
+	return (err);
+}
+
+static bool
+extent_purge_lazy_hook(extent_hooks_t *extent_hooks, void *addr, size_t size,
+    size_t offset, size_t length, unsigned arena_ind)
+{
+	bool err;
+
+	TRACE_HOOK("%s(extent_hooks=%p, addr=%p, size=%zu, offset=%zu, "
+	    "length=%zu arena_ind=%u)\n", __func__, extent_hooks, addr, size,
+	    offset, length, arena_ind);
+	assert_ptr_eq(extent_hooks, &hooks,
+	    "extent_hooks should be same as pointer used to set hooks");
+	assert_ptr_eq(extent_hooks->purge_lazy, extent_purge_lazy_hook,
+	    "Wrong hook function");
+	called_purge_lazy = true;
+	if (!try_purge_lazy)
+		return (true);
+	err = default_hooks->purge_lazy == NULL ||
+	    default_hooks->purge_lazy(default_hooks, addr, size, offset, length,
+	    0);
+	did_purge_lazy = !err;
+	return (err);
+}
+
+static bool
+extent_purge_forced_hook(extent_hooks_t *extent_hooks, void *addr, size_t size,
+    size_t offset, size_t length, unsigned arena_ind)
+{
+	bool err;
+
+	TRACE_HOOK("%s(extent_hooks=%p, addr=%p, size=%zu, offset=%zu, "
+	    "length=%zu arena_ind=%u)\n", __func__, extent_hooks, addr, size,
+	    offset, length, arena_ind);
+	assert_ptr_eq(extent_hooks, &hooks,
+	    "extent_hooks should be same as pointer used to set hooks");
+	assert_ptr_eq(extent_hooks->purge_forced, extent_purge_forced_hook,
+	    "Wrong hook function");
+	called_purge_forced = true;
+	if (!try_purge_forced)
+		return (true);
+	err = default_hooks->purge_forced == NULL ||
+	    default_hooks->purge_forced(default_hooks, addr, size, offset,
+	    length, 0);
+	did_purge_forced = !err;
+	return (err);
+}
+
+static bool
+extent_split_hook(extent_hooks_t *extent_hooks, void *addr, size_t size,
+    size_t size_a, size_t size_b, bool committed, unsigned arena_ind)
+{
+	bool err;
+
+	TRACE_HOOK("%s(extent_hooks=%p, addr=%p, size=%zu, size_a=%zu, "
+	    "size_b=%zu, committed=%s, arena_ind=%u)\n", __func__, extent_hooks,
+	    addr, size, size_a, size_b, committed ? "true" : "false",
+	    arena_ind);
+	assert_ptr_eq(extent_hooks, &hooks,
+	    "extent_hooks should be same as pointer used to set hooks");
+	assert_ptr_eq(extent_hooks->split, extent_split_hook,
+	    "Wrong hook function");
+	called_split = true;
+	if (!try_split)
+		return (true);
+	err = (default_hooks->split == NULL ||
+	    default_hooks->split(default_hooks, addr, size, size_a, size_b,
+	    committed, 0));
+	did_split = !err;
+	return (err);
+}
+
+static bool
+extent_merge_hook(extent_hooks_t *extent_hooks, void *addr_a, size_t size_a,
+    void *addr_b, size_t size_b, bool committed, unsigned arena_ind)
+{
+	bool err;
+
+	TRACE_HOOK("%s(extent_hooks=%p, addr_a=%p, size_a=%zu, addr_b=%p "
+	    "size_b=%zu, committed=%s, arena_ind=%u)\n", __func__, extent_hooks,
+	    addr_a, size_a, addr_b, size_b, committed ? "true" : "false",
+	    arena_ind);
+	assert_ptr_eq(extent_hooks, &hooks,
+	    "extent_hooks should be same as pointer used to set hooks");
+	assert_ptr_eq(extent_hooks->merge, extent_merge_hook,
+	    "Wrong hook function");
+	called_merge = true;
+	if (!try_merge)
+		return (true);
+	err = (default_hooks->merge == NULL ||
+	    default_hooks->merge(default_hooks, addr_a, size_a, addr_b, size_b,
+	    committed, 0));
+	did_merge = !err;
+	return (err);
+}
+
+static void
+extent_hooks_prep(void)
+{
+	size_t sz;
+
+	sz = sizeof(default_hooks);
+	assert_d_eq(mallctl("arena.0.extent_hooks", (void *)&default_hooks, &sz,
+	    NULL, 0), 0, "Unexpected mallctl() error");
+}
diff --git a/test/integration/extent.c b/test/integration/extent.c
index 6be3b836..e347b66d 100644
--- a/test/integration/extent.c
+++ b/test/integration/extent.c
@@ -4,204 +4,7 @@
 const char *malloc_conf = "junk:false";
 #endif
 
-static void	*extent_alloc(extent_hooks_t *extent_hooks, void *new_addr,
-    size_t size, size_t alignment, bool *zero, bool *commit,
-    unsigned arena_ind);
-static bool	extent_dalloc(extent_hooks_t *extent_hooks, void *addr,
-    size_t size, bool committed, unsigned arena_ind);
-static bool	extent_commit(extent_hooks_t *extent_hooks, void *addr,
-    size_t size, size_t offset, size_t length, unsigned arena_ind);
-static bool	extent_decommit(extent_hooks_t *extent_hooks, void *addr,
-    size_t size, size_t offset, size_t length, unsigned arena_ind);
-static bool	extent_purge_lazy(extent_hooks_t *extent_hooks, void *addr,
-    size_t size, size_t offset, size_t length, unsigned arena_ind);
-static bool	extent_purge_forced(extent_hooks_t *extent_hooks, void *addr,
-    size_t size, size_t offset, size_t length, unsigned arena_ind);
-static bool	extent_split(extent_hooks_t *extent_hooks, void *addr,
-    size_t size, size_t size_a, size_t size_b, bool committed,
-    unsigned arena_ind);
-static bool	extent_merge(extent_hooks_t *extent_hooks, void *addr_a,
-    size_t size_a, void *addr_b, size_t size_b, bool committed,
-    unsigned arena_ind);
-
-static extent_hooks_t hooks = {
-	extent_alloc,
-	extent_dalloc,
-	extent_commit,
-	extent_decommit,
-	extent_purge_lazy,
-	extent_purge_forced,
-	extent_split,
-	extent_merge
-};
-static extent_hooks_t *new_hooks = &hooks;
-static extent_hooks_t *orig_hooks;
-static extent_hooks_t *old_hooks;
-
-static bool do_dalloc = true;
-static bool do_decommit;
-
-static bool did_alloc;
-static bool did_dalloc;
-static bool did_commit;
-static bool did_decommit;
-static bool did_purge_lazy;
-static bool did_purge_forced;
-static bool tried_split;
-static bool did_split;
-static bool did_merge;
-
-#if 0
-#  define TRACE_HOOK(fmt, ...) malloc_printf(fmt, __VA_ARGS__)
-#else
-#  define TRACE_HOOK(fmt, ...)
-#endif
-
-static void *
-extent_alloc(extent_hooks_t *extent_hooks, void *new_addr, size_t size,
-    size_t alignment, bool *zero, bool *commit, unsigned arena_ind)
-{
-
-	TRACE_HOOK("%s(extent_hooks=%p, new_addr=%p, size=%zu, alignment=%zu, "
-	    "*zero=%s, *commit=%s, arena_ind=%u)\n", __func__, extent_hooks,
-	    new_addr, size, alignment, *zero ?  "true" : "false", *commit ?
-	    "true" : "false", arena_ind);
-	assert_ptr_eq(extent_hooks, new_hooks,
-	    "extent_hooks should be same as pointer used to set hooks");
-	assert_ptr_eq(extent_hooks->alloc, extent_alloc, "Wrong hook function");
-	did_alloc = true;
-	return (old_hooks->alloc(old_hooks, new_addr, size, alignment, zero,
-	    commit, 0));
-}
-
-static bool
-extent_dalloc(extent_hooks_t *extent_hooks, void *addr, size_t size,
-    bool committed, unsigned arena_ind)
-{
-
-	TRACE_HOOK("%s(extent_hooks=%p, addr=%p, size=%zu, committed=%s, "
-	    "arena_ind=%u)\n", __func__, extent_hooks, addr, size, committed ?
-	    "true" : "false", arena_ind);
-	assert_ptr_eq(extent_hooks, new_hooks,
-	    "extent_hooks should be same as pointer used to set hooks");
-	assert_ptr_eq(extent_hooks->dalloc, extent_dalloc,
-	    "Wrong hook function");
-	did_dalloc = true;
-	if (!do_dalloc)
-		return (true);
-	return (old_hooks->dalloc(old_hooks, addr, size, committed, 0));
-}
-
-static bool
-extent_commit(extent_hooks_t *extent_hooks, void *addr, size_t size,
-    size_t offset, size_t length, unsigned arena_ind)
-{
-	bool err;
-
-	TRACE_HOOK("%s(extent_hooks=%p, addr=%p, size=%zu, offset=%zu, "
-	    "length=%zu, arena_ind=%u)\n", __func__, extent_hooks, addr, size,
-	    offset, length, arena_ind);
-	assert_ptr_eq(extent_hooks, new_hooks,
-	    "extent_hooks should be same as pointer used to set hooks");
-	assert_ptr_eq(extent_hooks->commit, extent_commit,
-	    "Wrong hook function");
-	err = old_hooks->commit(old_hooks, addr, size, offset, length, 0);
-	did_commit = !err;
-	return (err);
-}
-
-static bool
-extent_decommit(extent_hooks_t *extent_hooks, void *addr, size_t size,
-    size_t offset, size_t length, unsigned arena_ind)
-{
-	bool err;
-
-	TRACE_HOOK("%s(extent_hooks=%p, addr=%p, size=%zu, offset=%zu, "
-	    "length=%zu, arena_ind=%u)\n", __func__, extent_hooks, addr, size,
-	    offset, length, arena_ind);
-	assert_ptr_eq(extent_hooks, new_hooks,
-	    "extent_hooks should be same as pointer used to set hooks");
-	assert_ptr_eq(extent_hooks->decommit, extent_decommit,
-	    "Wrong hook function");
-	if (!do_decommit)
-		return (true);
-	err = old_hooks->decommit(old_hooks, addr, size, offset, length, 0);
-	did_decommit = !err;
-	return (err);
-}
-
-static bool
-extent_purge_lazy(extent_hooks_t *extent_hooks, void *addr, size_t size,
-    size_t offset, size_t length, unsigned arena_ind)
-{
-
-	TRACE_HOOK("%s(extent_hooks=%p, addr=%p, size=%zu, offset=%zu, "
-	    "length=%zu arena_ind=%u)\n", __func__, extent_hooks, addr, size,
-	    offset, length, arena_ind);
-	assert_ptr_eq(extent_hooks, new_hooks,
-	    "extent_hooks should be same as pointer used to set hooks");
-	assert_ptr_eq(extent_hooks->purge_lazy, extent_purge_lazy,
-	    "Wrong hook function");
-	did_purge_lazy = true;
-	return (old_hooks->purge_lazy == NULL ||
-	    old_hooks->purge_lazy(old_hooks, addr, size, offset, length, 0));
-}
-
-static bool
-extent_purge_forced(extent_hooks_t *extent_hooks, void *addr, size_t size,
-    size_t offset, size_t length, unsigned arena_ind)
-{
-
-	TRACE_HOOK("%s(extent_hooks=%p, addr=%p, size=%zu, offset=%zu, "
-	    "length=%zu arena_ind=%u)\n", __func__, extent_hooks, addr, size,
-	    offset, length, arena_ind);
-	assert_ptr_eq(extent_hooks, new_hooks,
-	    "extent_hooks should be same as pointer used to set hooks");
-	assert_ptr_eq(extent_hooks->purge_forced, extent_purge_forced,
-	    "Wrong hook function");
-	did_purge_forced = true;
-	return (old_hooks->purge_forced == NULL ||
-	    old_hooks->purge_forced(old_hooks, addr, size, offset, length, 0));
-}
-
-static bool
-extent_split(extent_hooks_t *extent_hooks, void *addr, size_t size,
-    size_t size_a, size_t size_b, bool committed, unsigned arena_ind)
-{
-	bool err;
-
-	TRACE_HOOK("%s(extent_hooks=%p, addr=%p, size=%zu, size_a=%zu, "
-	    "size_b=%zu, committed=%s, arena_ind=%u)\n", __func__, extent_hooks,
-	    addr, size, size_a, size_b, committed ? "true" : "false",
-	    arena_ind);
-	assert_ptr_eq(extent_hooks, new_hooks,
-	    "extent_hooks should be same as pointer used to set hooks");
-	assert_ptr_eq(extent_hooks->split, extent_split, "Wrong hook function");
-	tried_split = true;
-	err = (old_hooks->split == NULL || old_hooks->split(old_hooks, addr,
-	    size, size_a, size_b, committed, 0));
-	did_split = !err;
-	return (err);
-}
-
-static bool
-extent_merge(extent_hooks_t *extent_hooks, void *addr_a, size_t size_a,
-    void *addr_b, size_t size_b, bool committed, unsigned arena_ind)
-{
-	bool err;
-
-	TRACE_HOOK("%s(extent_hooks=%p, addr_a=%p, size_a=%zu, addr_b=%p "
-	    "size_b=%zu, committed=%s, arena_ind=%u)\n", __func__, extent_hooks,
-	    addr_a, size_a, addr_b, size_b, committed ? "true" : "false",
-	    arena_ind);
-	assert_ptr_eq(extent_hooks, new_hooks,
-	    "extent_hooks should be same as pointer used to set hooks");
-	assert_ptr_eq(extent_hooks->merge, extent_merge, "Wrong hook function");
-	err = (old_hooks->merge == NULL || old_hooks->merge(old_hooks, addr_a,
-	    size_a, addr_b, size_b, committed, 0));
-	did_merge = !err;
-	return (err);
-}
+#include "test/extent_hooks.h"
 
 static void
 test_extent_body(unsigned arena_ind)
@@ -229,37 +32,36 @@ test_extent_body(unsigned arena_ind)
 	assert_d_eq(mallctlnametomib("arena.0.purge", purge_mib, &purge_miblen),
 	    0, "Unexpected mallctlnametomib() failure");
 	purge_mib[1] = (size_t)arena_ind;
-	do_dalloc = false;
-	do_decommit = false;
+	try_dalloc = false;
+	try_decommit = false;
 	p = mallocx(large0 * 2, flags);
 	assert_ptr_not_null(p, "Unexpected mallocx() error");
-	did_dalloc = false;
-	did_decommit = false;
+	called_dalloc = false;
+	called_decommit = false;
 	did_purge_lazy = false;
 	did_purge_forced = false;
-	tried_split = false;
-	did_split = false;
+	called_split = false;
 	xallocx_success_a = (xallocx(p, large0, 0, flags) == large0);
 	assert_d_eq(mallctlbymib(purge_mib, purge_miblen, NULL, NULL, NULL, 0),
 	    0, "Unexpected arena.%u.purge error", arena_ind);
 	if (xallocx_success_a) {
-		assert_true(did_dalloc, "Expected dalloc");
-		assert_false(did_decommit, "Unexpected decommit");
+		assert_true(called_dalloc, "Expected dalloc call");
+		assert_true(called_decommit, "Expected decommit call");
 		assert_true(did_purge_lazy || did_purge_forced,
 		    "Expected purge");
 	}
-	assert_true(tried_split, "Expected split");
+	assert_true(called_split, "Expected split call");
 	dallocx(p, flags);
-	do_dalloc = true;
+	try_dalloc = true;
 
 	/* Test decommit/commit and observe split/merge. */
-	do_dalloc = false;
-	do_decommit = true;
+	try_dalloc = false;
+	try_decommit = true;
 	p = mallocx(large0 * 2, flags);
 	assert_ptr_not_null(p, "Unexpected mallocx() error");
 	did_decommit = false;
 	did_commit = false;
-	tried_split = false;
+	called_split = false;
 	did_split = false;
 	did_merge = false;
 	xallocx_success_b = (xallocx(p, large0, 0, flags) == large0);
@@ -275,8 +77,8 @@ test_extent_body(unsigned arena_ind)
 	if (xallocx_success_b && xallocx_success_c)
 		assert_true(did_merge, "Expected merge");
 	dallocx(p, flags);
-	do_dalloc = true;
-	do_decommit = false;
+	try_dalloc = true;
+	try_decommit = false;
 
 	/* Make sure non-large allocation succeeds. */
 	p = mallocx(42, flags);
@@ -290,6 +92,9 @@ TEST_BEGIN(test_extent_manual_hook)
 	size_t old_size, new_size, sz;
 	size_t hooks_mib[3];
 	size_t hooks_miblen;
+	extent_hooks_t *new_hooks, *old_hooks;
+
+	extent_hooks_prep();
 
 	sz = sizeof(unsigned);
 	assert_d_eq(mallctl("arenas.create", (void *)&arena_ind, &sz, NULL, 0),
@@ -301,24 +106,27 @@ TEST_BEGIN(test_extent_manual_hook)
 	    &hooks_miblen), 0, "Unexpected mallctlnametomib() failure");
 	hooks_mib[1] = (size_t)arena_ind;
 	old_size = sizeof(extent_hooks_t *);
+	new_hooks = &hooks;
 	new_size = sizeof(extent_hooks_t *);
 	assert_d_eq(mallctlbymib(hooks_mib, hooks_miblen, (void *)&old_hooks,
 	    &old_size, (void *)&new_hooks, new_size), 0,
 	    "Unexpected extent_hooks error");
-	orig_hooks = old_hooks;
-	assert_ptr_ne(old_hooks->alloc, extent_alloc, "Unexpected alloc error");
-	assert_ptr_ne(old_hooks->dalloc, extent_dalloc,
-	    "Unexpected dalloc error");
-	assert_ptr_ne(old_hooks->commit, extent_commit,
-	    "Unexpected commit error");
-	assert_ptr_ne(old_hooks->decommit, extent_decommit,
-	    "Unexpected decommit error");
-	assert_ptr_ne(old_hooks->purge_lazy, extent_purge_lazy,
-	    "Unexpected purge_lazy error");
-	assert_ptr_ne(old_hooks->purge_forced, extent_purge_forced,
-	    "Unexpected purge_forced error");
-	assert_ptr_ne(old_hooks->split, extent_split, "Unexpected split error");
-	assert_ptr_ne(old_hooks->merge, extent_merge, "Unexpected merge error");
+	assert_ptr_ne(old_hooks->alloc, extent_alloc_hook,
+	    "Unexpected extent_hooks error");
+	assert_ptr_ne(old_hooks->dalloc, extent_dalloc_hook,
+	    "Unexpected extent_hooks error");
+	assert_ptr_ne(old_hooks->commit, extent_commit_hook,
+	    "Unexpected extent_hooks error");
+	assert_ptr_ne(old_hooks->decommit, extent_decommit_hook,
+	    "Unexpected extent_hooks error");
+	assert_ptr_ne(old_hooks->purge_lazy, extent_purge_lazy_hook,
+	    "Unexpected extent_hooks error");
+	assert_ptr_ne(old_hooks->purge_forced, extent_purge_forced_hook,
+	    "Unexpected extent_hooks error");
+	assert_ptr_ne(old_hooks->split, extent_split_hook,
+	    "Unexpected extent_hooks error");
+	assert_ptr_ne(old_hooks->merge, extent_merge_hook,
+	    "Unexpected extent_hooks error");
 
 	test_extent_body(arena_ind);
 
@@ -327,23 +135,23 @@ TEST_BEGIN(test_extent_manual_hook)
 	    (void *)&old_hooks, new_size), 0, "Unexpected extent_hooks error");
 	assert_d_eq(mallctlbymib(hooks_mib, hooks_miblen, (void *)&old_hooks,
 	    &old_size, NULL, 0), 0, "Unexpected extent_hooks error");
-	assert_ptr_eq(old_hooks, orig_hooks, "Unexpected hooks error");
-	assert_ptr_eq(old_hooks->alloc, orig_hooks->alloc,
-	    "Unexpected alloc error");
-	assert_ptr_eq(old_hooks->dalloc, orig_hooks->dalloc,
-	    "Unexpected dalloc error");
-	assert_ptr_eq(old_hooks->commit, orig_hooks->commit,
-	    "Unexpected commit error");
-	assert_ptr_eq(old_hooks->decommit, orig_hooks->decommit,
-	    "Unexpected decommit error");
-	assert_ptr_eq(old_hooks->purge_lazy, orig_hooks->purge_lazy,
-	    "Unexpected purge_lazy error");
-	assert_ptr_eq(old_hooks->purge_forced, orig_hooks->purge_forced,
-	    "Unexpected purge_forced error");
-	assert_ptr_eq(old_hooks->split, orig_hooks->split,
-	    "Unexpected split error");
-	assert_ptr_eq(old_hooks->merge, orig_hooks->merge,
-	    "Unexpected merge error");
+	assert_ptr_eq(old_hooks, default_hooks, "Unexpected extent_hooks error");
+	assert_ptr_eq(old_hooks->alloc, default_hooks->alloc,
+	    "Unexpected extent_hooks error");
+	assert_ptr_eq(old_hooks->dalloc, default_hooks->dalloc,
+	    "Unexpected extent_hooks error");
+	assert_ptr_eq(old_hooks->commit, default_hooks->commit,
+	    "Unexpected extent_hooks error");
+	assert_ptr_eq(old_hooks->decommit, default_hooks->decommit,
+	    "Unexpected extent_hooks error");
+	assert_ptr_eq(old_hooks->purge_lazy, default_hooks->purge_lazy,
+	    "Unexpected extent_hooks error");
+	assert_ptr_eq(old_hooks->purge_forced, default_hooks->purge_forced,
+	    "Unexpected extent_hooks error");
+	assert_ptr_eq(old_hooks->split, default_hooks->split,
+	    "Unexpected extent_hooks error");
+	assert_ptr_eq(old_hooks->merge, default_hooks->merge,
+	    "Unexpected extent_hooks error");
 }
 TEST_END
 
@@ -351,8 +159,12 @@ TEST_BEGIN(test_extent_auto_hook)
 {
 	unsigned arena_ind;
 	size_t new_size, sz;
+	extent_hooks_t *new_hooks;
+
+	extent_hooks_prep();
 
 	sz = sizeof(unsigned);
+	new_hooks = &hooks;
 	new_size = sizeof(extent_hooks_t *);
 	assert_d_eq(mallctl("arenas.create", (void *)&arena_ind, &sz,
 	    (void *)&new_hooks, new_size), 0, "Unexpected mallctl() failure");
diff --git a/test/unit/base.c b/test/unit/base.c
index 6a082a5e..8f97e8bf 100644
--- a/test/unit/base.c
+++ b/test/unit/base.c
@@ -1,27 +1,6 @@
 #include "test/jemalloc_test.h"
 
-static void	*extent_alloc_hook(extent_hooks_t *extent_hooks, void *new_addr,
-    size_t size, size_t alignment, bool *zero, bool *commit,
-    unsigned arena_ind);
-static bool	extent_dalloc_hook(extent_hooks_t *extent_hooks, void *addr,
-    size_t size, bool committed, unsigned arena_ind);
-static bool	extent_decommit_hook(extent_hooks_t *extent_hooks, void *addr,
-    size_t size, size_t offset, size_t length, unsigned arena_ind);
-static bool	extent_purge_lazy_hook(extent_hooks_t *extent_hooks, void *addr,
-    size_t size, size_t offset, size_t length, unsigned arena_ind);
-static bool	extent_purge_forced_hook(extent_hooks_t *extent_hooks,
-    void *addr, size_t size, size_t offset, size_t length, unsigned arena_ind);
-
-static extent_hooks_t hooks_not_null = {
-	extent_alloc_hook,
-	extent_dalloc_hook,
-	NULL, /* commit */
-	extent_decommit_hook,
-	extent_purge_lazy_hook,
-	extent_purge_forced_hook,
-	NULL, /* split */
-	NULL /* merge */
-};
+#include "test/extent_hooks.h"
 
 static extent_hooks_t hooks_null = {
 	extent_alloc_hook,
@@ -34,80 +13,16 @@ static extent_hooks_t hooks_null = {
 	NULL /* merge */
 };
 
-static bool	did_alloc;
-static bool	did_dalloc;
-static bool	did_decommit;
-static bool	did_purge_lazy;
-static bool	did_purge_forced;
-
-#if 0
-#  define TRACE_HOOK(fmt, ...) malloc_printf(fmt, __VA_ARGS__)
-#else
-#  define TRACE_HOOK(fmt, ...)
-#endif
-
-static void *
-extent_alloc_hook(extent_hooks_t *extent_hooks, void *new_addr, size_t size,
-    size_t alignment, bool *zero, bool *commit, unsigned arena_ind)
-{
-
-	TRACE_HOOK("%s(extent_hooks=%p, new_addr=%p, size=%zu, alignment=%zu, "
-	    "*zero=%s, *commit=%s, arena_ind=%u)\n", __func__, extent_hooks,
-	    new_addr, size, alignment, *zero ?  "true" : "false", *commit ?
-	    "true" : "false", arena_ind);
-	did_alloc = true;
-	return (extent_hooks_default.alloc(
-	    (extent_hooks_t *)&extent_hooks_default, new_addr, size, alignment,
-	    zero, commit, 0));
-}
-
-static bool
-extent_dalloc_hook(extent_hooks_t *extent_hooks, void *addr, size_t size,
-    bool committed, unsigned arena_ind)
-{
-
-	TRACE_HOOK("%s(extent_hooks=%p, addr=%p, size=%zu, committed=%s, "
-	    "arena_ind=%u)\n", __func__, extent_hooks, addr, size, committed ?
-	    "true" : "false", arena_ind);
-	did_dalloc = true;
-	return (true); /* Cause cascade. */
-}
-
-static bool
-extent_decommit_hook(extent_hooks_t *extent_hooks, void *addr, size_t size,
-    size_t offset, size_t length, unsigned arena_ind)
-{
-
-	TRACE_HOOK("%s(extent_hooks=%p, addr=%p, size=%zu, offset=%zu, "
-	    "length=%zu, arena_ind=%u)\n", __func__, extent_hooks, addr, size,
-	    offset, length, arena_ind);
-	did_decommit = true;
-	return (true); /* Cause cascade. */
-}
-
-static bool
-extent_purge_lazy_hook(extent_hooks_t *extent_hooks, void *addr, size_t size,
-    size_t offset, size_t length, unsigned arena_ind)
-{
-
-	TRACE_HOOK("%s(extent_hooks=%p, addr=%p, size=%zu, offset=%zu, "
-	    "length=%zu arena_ind=%u)\n", __func__, extent_hooks, addr, size,
-	    offset, length, arena_ind);
-	did_purge_lazy = true;
-	return (true); /* Cause cascade. */
-}
-
-static bool
-extent_purge_forced_hook(extent_hooks_t *extent_hooks, void *addr, size_t size,
-    size_t offset, size_t length, unsigned arena_ind)
-{
-
-	TRACE_HOOK("%s(extent_hooks=%p, addr=%p, size=%zu, offset=%zu, "
-	    "length=%zu arena_ind=%u)\n", __func__, extent_hooks, addr, size,
-	    offset, length, arena_ind);
-	did_purge_forced = true;
-	return (true); /* Cause cascade. */
-}
+static extent_hooks_t hooks_not_null = {
+	extent_alloc_hook,
+	extent_dalloc_hook,
+	NULL, /* commit */
+	extent_decommit_hook,
+	extent_purge_lazy_hook,
+	extent_purge_forced_hook,
+	NULL, /* split */
+	NULL /* merge */
+};
 
 TEST_BEGIN(test_base_hooks_default)
 {
@@ -135,12 +50,21 @@ TEST_END
 
 TEST_BEGIN(test_base_hooks_null)
 {
+	extent_hooks_t hooks_orig;
 	tsdn_t *tsdn;
 	base_t *base;
 	size_t allocated0, allocated1, resident, mapped;
 
+	extent_hooks_prep();
+	try_dalloc = false;
+	try_decommit = false;
+	try_purge_lazy = false;
+	try_purge_forced = false;
+	memcpy(&hooks_orig, &hooks, sizeof(extent_hooks_t));
+	memcpy(&hooks, &hooks_null, sizeof(extent_hooks_t));
+
 	tsdn = tsdn_fetch();
-	base = base_new(tsdn, 0, (extent_hooks_t *)&hooks_null);
+	base = base_new(tsdn, 0, &hooks);
 	assert_ptr_not_null(base, "Unexpected base_new() failure");
 
 	base_stats_get(tsdn, base, &allocated0, &resident, &mapped);
@@ -155,20 +79,31 @@ TEST_BEGIN(test_base_hooks_null)
 	    "At least 42 bytes were allocated by base_alloc()");
 
 	base_delete(base);
+
+	memcpy(&hooks, &hooks_orig, sizeof(extent_hooks_t));
 }
 TEST_END
 
 TEST_BEGIN(test_base_hooks_not_null)
 {
+	extent_hooks_t hooks_orig;
 	tsdn_t *tsdn;
 	base_t *base;
 	void *p, *q, *r, *r_exp;
 
+	extent_hooks_prep();
+	try_dalloc = false;
+	try_decommit = false;
+	try_purge_lazy = false;
+	try_purge_forced = false;
+	memcpy(&hooks_orig, &hooks, sizeof(extent_hooks_t));
+	memcpy(&hooks, &hooks_not_null, sizeof(extent_hooks_t));
+
 	tsdn = tsdn_fetch();
 	did_alloc = false;
-	base = base_new(tsdn, 0, (extent_hooks_t *)&hooks_not_null);
+	base = base_new(tsdn, 0, &hooks);
 	assert_ptr_not_null(base, "Unexpected base_new() failure");
-	assert_true(did_alloc, "Expected alloc hook call");
+	assert_true(did_alloc, "Expected alloc");
 
 	/*
 	 * Check for tight packing at specified alignment under simple
@@ -254,12 +189,19 @@ TEST_BEGIN(test_base_hooks_not_null)
 		}
 	}
 
-	did_dalloc = did_decommit = did_purge_lazy = did_purge_forced = false;
+	called_dalloc = called_decommit = called_purge_lazy =
+	    called_purge_forced = false;
 	base_delete(base);
-	assert_true(did_dalloc, "Expected dalloc hook call");
-	assert_true(did_decommit, "Expected decommit hook call");
-	assert_true(did_purge_lazy, "Expected purge_lazy hook call");
-	assert_true(did_purge_forced, "Expected purge_forced hook call");
+	assert_true(called_dalloc, "Expected dalloc call");
+	assert_true(called_decommit, "Expected decommit call");
+	assert_true(called_purge_lazy, "Expected purge_lazy call");
+	assert_true(called_purge_forced, "Expected purge_forced call");
+
+	try_dalloc = true;
+	try_decommit = true;
+	try_purge_lazy = true;
+	try_purge_forced = true;
+	memcpy(&hooks, &hooks_orig, sizeof(extent_hooks_t));
 }
 TEST_END