Avoid a bunch of duplication

test/mechanicaldiff.bats

@@ -47,38 +47,12 @@ setup() {
 	ten
 	delta
 	EOF
-  cat >"$BATS_TEST_TMPDIR/new" <<-'EOF'
+  sed \
-	alpha
+    -e 's/beta/beta_changed/' \
-	beta_changed
+    -e 's/delta/delta_changed/' \
-	gamma
+    "$BATS_TEST_TMPDIR/old" >"$BATS_TEST_TMPDIR/new"
-	one
+  sed 's/beta/beta_changed/' "$BATS_TEST_TMPDIR/old" \
-	two
+    >"$BATS_TEST_TMPDIR/new_kept"
-	three
-	four
-	five
-	six
-	seven
-	eight
-	nine
-	ten
-	delta_changed
-	EOF
-  cat >"$BATS_TEST_TMPDIR/new_kept" <<-'EOF'
-	alpha
-	beta_changed
-	gamma
-	one
-	two
-	three
-	four
-	five
-	six
-	seven
-	eight
-	nine
-	ten
-	delta
-	EOF
 
   git diff --no-index "$BATS_TEST_TMPDIR/old" \
     "$BATS_TEST_TMPDIR/new" \