[PATCH v3] binman: elf: Check for ELF_TOOLS availability in is_valid

[Tom Rini <trini@konsulko.com>]

From: Dmitrii Sharshakov <d3dx12.xx@gmail.com>

Check if elftools package is available before running DecodeElf().

This clarifies the error message and adds the required test for
coverage.

Signed-off-by: Dmitrii Sharshakov <d3dx12.xx@gmail.com>
Signed-off-by: Andrew Soknacki <asoknacki@gmail.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
[trini: Add the test provided by Andrew on IRC, to fix coverage]
Signed-off-by: Tom Rini <trini@konsulko.com>
---
Changes in v3:
- Add the test, provided by Andrew, to address the coverage failure in
  CI
---
 tools/binman/elf.py      |  2 ++
 tools/binman/elf_test.py | 12 ++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/tools/binman/elf.py b/tools/binman/elf.py
index 6ac960e04196..899c84ad36d6 100644
--- a/tools/binman/elf.py
+++ b/tools/binman/elf.py
@@ -570,6 +570,8 @@ def is_valid(data):
     Returns:
         bool: True if a valid Elf file, False if not
     """
+    if not ELF_TOOLS:
+        raise ValueError("Python: No module named 'elftools'")
     try:
         DecodeElf(data, 0)
         return True
diff --git a/tools/binman/elf_test.py b/tools/binman/elf_test.py
index 5b1733928986..3ad0bf4c4b09 100644
--- a/tools/binman/elf_test.py
+++ b/tools/binman/elf_test.py
@@ -373,6 +373,18 @@ class TestElf(unittest.TestCase):
         self.assertEqual(True, elf.is_valid(data))
         self.assertEqual(False, elf.is_valid(data[4:]))
 
+    def test_is_valid_fail(self):
+        """Test calling is_valid() without elftools"""
+        old_val = elf.ELF_TOOLS
+        try:
+            elf.ELF_TOOLS = False
+            with self.assertRaises(ValueError) as e:
+                elf.is_valid(b'')
+            self.assertIn("Python: No module named 'elftools'",
+                      str(e.exception))
+        finally:
+            elf.ELF_TOOLS = old_val
+
     def test_get_symbol_offset(self):
         fname = self.ElfTestFile('embed_data')
         syms = elf.GetSymbols(fname, ['embed_start', 'embed'])
-- 
2.43.0