[Libguestfs] [PATCH libnbd v2 3/3] copy/copy-nbd-error.sh: Make this test non-stochastic

[Richard W.M. Jones]

Because the test previously used error rates of 50%, it could
sometimes "fail to fail".  This is noticable if you run the test
repeatedly:

$ while make -C copy check TESTS=copy-nbd-error.sh >& /tmp/log ; do echo -n . ; done

This now happens more often because of the larger requests made by the
new multi-threaded loop, resulting in fewer calls to the error filter,
so a greater chance that a series of 50% coin tosses will come up all
heads in the test.

Fix this by making the test non-stocastic.

Fixes: commit 8d444b41d09a700c7ee6f9182a649f3f2d325abb
---
 copy/copy-nbd-error.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/copy/copy-nbd-error.sh b/copy/copy-nbd-error.sh
index 0088807f54..01524a890c 100755
--- a/copy/copy-nbd-error.sh
+++ b/copy/copy-nbd-error.sh
@@ -40,7 +40,7 @@ $VG nbdcopy -- [ nbdkit --exit-with-parent -v --filter=error pattern 5M \
 # Failure to read should be fatal
 echo "Testing read failures on non-sparse source"
 $VG nbdcopy -- [ nbdkit --exit-with-parent -v --filter=error pattern 5M \
-    error-pread-rate=0.5 ] null: && fail=1
+    error-pread-rate=1 ] null: && fail=1
 
 # However, reliable block status on a sparse image can avoid the need to read
 echo "Testing read failures on sparse source"
@@ -51,7 +51,7 @@ $VG nbdcopy -- [ nbdkit --exit-with-parent -v --filter=error null 5M \
 echo "Testing write data failures on arbitrary destination"
 $VG nbdcopy -- [ nbdkit --exit-with-parent -v pattern 5M ] \
     [ nbdkit --exit-with-parent -v --filter=error --filter=noextents \
-        memory 5M error-pwrite-rate=0.5 ] && fail=1
+        memory 5M error-pwrite-rate=1 ] && fail=1
 
 # However, writing zeroes can bypass the need for normal writes
 echo "Testing write data failures from sparse source"
-- 
2.37.0.rc2