diff --git a/flang/test/Semantics/test_errors.py b/flang/test/Semantics/test_errors.py
--- a/flang/test/Semantics/test_errors.py
+++ b/flang/test/Semantics/test_errors.py
@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 
-"""Compiles a source file and checks errors against those listed in the file.
+"""Compiles a source file and checks errors and warnings against those
+   listed in the file.
 
 Parameters:
     sys.argv[1]: a source file with contains the input and expected output
@@ -19,8 +20,10 @@
 srcdir = cm.set_source(sys.argv[1])
 with open(srcdir, 'r') as f:
     src = f.readlines()
-actual = ""
-expect = ""
+err_actual = ""
+err_expect = ""
+warn_actual = ""
+warn_expect = ""
 diffs = ""
 log = ""
 
@@ -34,6 +37,7 @@
     try:
         proc = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                               check=True, universal_newlines=True, cwd=tmpdir)
+        log = proc.stderr
     except subprocess.CalledProcessError as e:
         log = e.stderr
         if e.returncode >= 128:
@@ -44,25 +48,42 @@
 for line in log.split('\n'):
     m = re.search(r"[^:]*:(\d+:).*(?:error:)(.*)", line)
     if m:
-        actual += m.expand(r"\1\2\n")
+        err_actual += m.expand(r"\1\2\n")
+for line in log.split('\n'):
+    m = re.search(r"[^:]*:(\d+:).*(?:warning:|portability:)(.*)", line)
+    if m:
+        warn_actual += m.expand(r"\1\2\n")
 
-# Gets the expected errors and their line number
+# Gets the expected diagnostics and their line number
 errors = []
+warnings = []
 for i, line in enumerate(src, 1):
-    m = re.search(r"(?:^\s*!\s*ERROR: )(.*)", line)
-    if m:
-        errors.append(m.group(1))
+    me = re.search(r"(?:^\s*!\s*ERROR: )(.*)", line)
+    mw = re.search(r"(?:^\s*!\s*WARNING: )(.*)", line)
+    if me:
+        errors.append(me.group(1))
+        continue
+    if mw:
+        warnings.append(mw.group(1))
         continue
     if errors:
         for x in errors:
-            expect += f"{i}: {x}\n"
+            err_expect += f"{i}: {x}\n"
         errors = []
+    if warnings:
+        for x in warnings:
+            warn_expect += f"{i}: {x}\n"
+        warnings = []
 
-# Compares the expected errors with the compiler errors
-for line in unified_diff(actual.split("\n"), expect.split("\n"), n=0):
+# Compares the expected errors and warnings with the compiler diagnostics
+for line in unified_diff(err_actual.split("\n"), err_expect.split("\n"), n=0):
     line = re.sub(r"(^\-)(\d+:)", r"\nactual at \g<2>", line)
     line = re.sub(r"(^\+)(\d+:)", r"\nexpect at \g<2>", line)
     diffs += line
+for line in unified_diff(warn_actual.split("\n"), warn_expect.split("\n"), n=0):
+    line = re.sub(r"(^\-)(\d+:)", r"\nactual warning at \g<2>", line)
+    line = re.sub(r"(^\+)(\d+:)", r"\nexpected warning at \g<2>", line)
+    diffs += line
 
 if diffs != "":
     print(diffs)