Shell: Add some tests for heredocs

Author: https://github.com/alimpfard
Commit: https://github.com/SerenityOS/serenity/commit/d70f25bbe5c
Pull-request: https://github.com/SerenityOS/serenity/pull/6725
Issue: https://github.com/SerenityOS/serenity/issues/4283

Userland/Shell/Tests/heredocs.sh

@@ -0,0 +1,74 @@
+#!/bin/sh
+
+source $(dirname "$0")/test-commons.inc
+
+# Simple usage, single doc
+echo <<-test > sh.doc.test
+this is a test
+test
+if test "$(cat sh.doc.test)" != "this is a test" {
+    fail "Could not use normal interpolated heredoc"
+}
+
+echo <<-'test' > sh.doc.test
+this is a test
+test
+if test "$(cat sh.doc.test)" != "this is a test" {
+    fail "Could not use normal non-interpolated heredoc"
+}
+
+echo <<~test > sh.doc.test
+    this is a test
+test
+if test "$(cat sh.doc.test)" != "this is a test" {
+    fail "Could not use normal dedented heredoc"
+}
+
+echo <<~'test' > sh.doc.test
+    this is a test
+test
+if test "$(cat sh.doc.test)" != "this is a test" {
+    fail "Could not use normal non-interpolated dedented heredoc"
+}
+
+var=test
+echo <<-test > sh.doc.test
+this is a $var
+test
+if test "$(cat sh.doc.test)" != "this is a test" {
+    fail "Could not use interpolated heredoc with interpolation"
+}
+
+echo <<~test > sh.doc.test
+    this is a $var
+test
+if test "$(cat sh.doc.test)" != "this is a test" {
+    fail "Could not use dedented interpolated heredoc with interpolation"
+}
+
+# Multiple heredocs
+echo <<-test <<-test2 > sh.doc.test
+contents for test
+test
+contents for test2
+test2
+if test "$(cat sh.doc.test)" != "contents for test contents for test2" {
+    fail "Could not use two heredocs"
+}
+
+# Why would you do this you crazy person?
+if test "$(echo <<~text)" != "test" {
+                test
+                text
+    fail "Could not use heredocs in a weird place"
+}
+
+# Now let's try something _really_ weird!
+if test "$(echo <<~test1)" != "$(echo <<~test2)" { fail "The parser forgot about heredocs after a block, oops" }
+test
+test1
+test
+test2
+
+rm -f sh.doc.test
+pass