tests: Make test writing simpler and add two new tests.

Add a test_todo_session function to test-lib.sh that enables
easy recording of input and output from todo.sh (including
annotation of exit status for testing error cases).

Begin to port and re-factor testsuite.txt into smaller
test cases, starting with basic add list functionality
and replace functionality.

Thanks to Philippe Teuwen <phil@teuwen.org> for feedback
and improvements.

Signed-off-by: Emil Sit <sit@emilsit.net>

tests/t1000-addlist.sh

@@ -0,0 +1,58 @@
+#!/bin/sh
+
+test_description='basic add and list functionality
+
+This test just makes sure the basic add and list
+command work, including support for filtering.
+'
+. ./test-lib.sh
+
+#
+# Add and list
+#
+test_todo_session 'basic add/list' <<EOF
+>>> todo.sh add notice the daisies
+TODO: 'notice the daisies' added on line 1.
+
+>>> todo.sh list
+1 notice the daisies
+--
+TODO: 1 of 1 tasks shown from $HOME/todo.txt
+
+>>> todo.sh add smell the roses
+TODO: 'smell the roses' added on line 2.
+
+>>> todo.sh list
+1 notice the daisies
+2 smell the roses
+--
+TODO: 2 of 2 tasks shown from $HOME/todo.txt
+EOF
+
+#
+# Filter
+#
+test_todo_session 'basic list filtering' <<EOF
+>>> todo.sh list daisies
+1 notice the daisies
+--
+TODO: 1 of 2 tasks shown from $HOME/todo.txt
+
+>>> todo.sh list smell
+2 smell the roses
+--
+TODO: 1 of 2 tasks shown from $HOME/todo.txt
+EOF
+
+test_todo_session 'case-insensitive filtering' <<EOF
+>>> todo.sh add smell the uppercase Roses
+TODO: 'smell the uppercase Roses' added on line 3.
+
+>>> todo.sh list roses
+2 smell the roses
+3 smell the uppercase Roses
+--
+TODO: 2 of 3 tasks shown from $HOME/todo.txt
+EOF
+
+test_done