Add tests for slow IO

Author: ChrisJefferson

.travis.yml

@@ -17,6 +17,7 @@ addons:
     - libreadline-dev
     - python
     - python-pip
+    - perl
 
 #
 # The following test jobs are roughly sorted by duration, from longest to

tst/teststandard/processes/slowwrite.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env sh
+
+# We use printf here to allow the arguments to contain '\n'
+# so we can explictly control where newlines appear.
+printf "$2"
+sleep 1
+printf "$3"

tst/teststandard/processes/streamio.tst

@@ -0,0 +1,53 @@
+#@local scriptdir, write, checkPartialRead, process, c
+#
+gap> START_TEST("streamio.tst");
+gap> scriptdir := DirectoriesLibrary( "tst/teststandard/processes/" );;
+gap> write := Filename(scriptdir, "slowwrite.sh");;
+
+# Read the output of 'prog', using 'readfunc'. The output should
+# come in two parts, 'firstread' and 'secondread'.
+# If GAP is too slow, allow 'firstread' and 'secondread' to be read
+# in one step, but then return 'false'.
+# We run this function multiple times to avoid very occasional failures
+# due to OS scheduling.
+gap> checkPartialRead := function(prog, readfunc, firstread, secondread)
+> local process, l;
+> process := InputOutputLocalProcess(DirectoryCurrent(), prog, ["prog", firstread, secondread]);
+> l := ReadLine(process);
+> if l = Concatenation(firstread, secondread) then
+>   if ReadLine(process) <> fail then Error("Invalid end - type 1"); fi;
+>   CloseStream(process);
+>   return false;
+> else
+>   if ReadLine(process) <> secondread then Error("Missing second"); fi;
+>   if ReadLine(process) <> fail then Error("Invalid end - type 2"); fi;
+>   CloseStream(process);
+>   return true;
+> fi;
+> end;;
+gap> ForAny([1..10], x -> checkPartialRead(write, ReadLine, "aaa", "aaa\n"));
+true
+gap> ForAny([1..10], x -> checkPartialRead(write, ReadLine, "aaa", "aaa"));
+true
+gap> ForAny([1..10], x -> checkPartialRead(write, ReadAll, "aaa", "aaa\n"));
+true
+
+# Read as bytes, which is always identical
+gap> process := InputOutputLocalProcess(DirectoryCurrent(), write, ["prog", "abc", "def"]);
+< input/output stream to slowwrite.sh >
+gap> c := ReadByte(process);
+97
+gap> c := ReadByte(process);
+98
+gap> c := ReadByte(process);
+99
+gap> c := ReadByte(process);
+100
+gap> c := ReadByte(process);
+101
+gap> c := ReadByte(process);
+102
+gap> c := ReadByte(process);
+fail
+gap> CloseStream(process);
+gap> STOP_TEST("streamio.tst", 1);