Added output expectation handler

src/expect-core

@@ -26,3 +26,20 @@ __INC_EXPECT_CORE=1
 _expect--succeed() { test "$1" -eq 0; }
 _expect--fail()    { test "$1" -ne 0; }
 
+_expect--output()
+{
+  local -r cmp="$2"
+  shift 2
+  local -r clause="$*"
+
+  local nl=
+  if [ -n "$clause" ]; then
+    [ "$clause" == 'without newline' ] \
+      && nl=-n \
+      || _bail "unrecognized output clause: $clause"
+  fi
+
+  # we will eventually be interested in this output
+  diff <( echo $nl "$cmp" ) - &>/dev/null
+}
+

test/test-expect-core

@@ -45,3 +45,37 @@ describe fail
   end
 end
 
+
+describe output
+  it will default to asserting against stdout
+    expect _expect--output 0 "test string" <<< "test string"
+      to succeed
+  end
+
+  it ignores exit code
+    expect _expect--output 1 "foo" <<< "foo"
+      to succeed
+  end
+
+  it fails on output mismatch
+    expect _expect--output 0 "foo" <<< "bar"
+      to fail
+  end
+
+  # as is good practice for Unix utilities
+  it expects trailing newline by default
+    expect _expect--output 0 "foo" < <( echo -n foo )
+      to fail
+  end
+
+  it can disable trailing newline check with "'without newline'" clause
+    expect _expect--output 0 "foo" without newline < <( echo -n foo )
+      to succeed
+  end
+
+  it errors on any unrecognized clause
+    expect _expect--output 0 "foo" fluffy bunnies <<< "foo"
+      to fail
+  end
+end
+