Add test for plain text $include.

tests/cwl/misc/cl-include-text.cwl

@@ -0,0 +1,23 @@
+#!/usr/bin/env cwl-runner
+class: CommandLineTool
+cwlVersion: v1.0
+
+requirements:
+  InitialWorkDirRequirement:
+    listing:
+    - entryname: text1.txt
+      entry:
+        $include: text1.txt
+
+inputs:
+  one:
+    type: string
+
+outputs:
+  output:
+    type: stdout
+stdout: text1.out
+
+baseCommand:
+- cat
+- text1.txt

tests/cwl/misc/text1.txt

@@ -0,0 +1,2 @@
+We hold these truths to be self-evident, 
+that all men are created equal

tests/test_code_intelligence.py

@@ -116,6 +116,17 @@ def test_remote_files():
     assert hov.contents.value == "```\n\n```"
 
 
+def test_plain_text_include():
+    this_path = current_path / "cwl" / "misc" / "cl-include-text.cwl"
+    doc = load(doc_path=this_path, type_dicts=type_dicts)
+
+    assert len(doc.problems) == 0
+
+    hov = doc.hover(Position(9, 21))
+    assert "We hold" in hov.contents.value
+    # Hover should show contents of included file
+
+
 def test_schemadef_import():
     this_path = current_path / "cwl" / "misc" / "cl-schemadef-import.cwl"
     doc = load(doc_path=this_path, type_dicts=type_dicts)