[iwyu_tool] Add test for compilation db path canonicalization

This drove out a refactor to read the file separately from
canonicalization for easier testing.

2 files changed, 33 insertions, 13 deletions

diff --git a/iwyu_tool.py b/iwyu_tool.py
index 7b11156..94f2fdb 100755
--- a/iwyu_tool.py
+++ b/iwyu_tool.py
@@ -295,19 +295,10 @@ class Invocation(object):
         return Process.start(self)
 
 
-def parse_compilation_db(compilation_db_path):
-    """ Parse JSON compilation database and return a canonicalized form. """
-    if os.path.isdir(compilation_db_path):
-        compilation_db_path = os.path.join(compilation_db_path,
-                                           'compile_commands.json')
-
-    # Read compilation db from disk.
-    compilation_db_path = os.path.realpath(compilation_db_path)
-    with open(compilation_db_path, 'r') as fileobj:
-        compilation_db = json.load(fileobj)
-
-    # Expand symlinks.
+def fixup_compilation_db(compilation_db):
+    """ Canonicalize paths in JSON compilation database. """
     for entry in compilation_db:
+        # Expand relative paths and symlinks
         entry['file'] = os.path.realpath(entry['file'])
 
     return compilation_db
@@ -366,11 +357,19 @@ def main(compilation_db_path, source_files, verbose, formatter, jobs,
     """ Entry point. """
 
     try:
-        compilation_db = parse_compilation_db(compilation_db_path)
+        if os.path.isdir(compilation_db_path):
+            compilation_db_path = os.path.join(compilation_db_path,
+                                               'compile_commands.json')
+
+        # Read compilation db from disk.
+        compilation_db_path = os.path.realpath(compilation_db_path)
+        with open(compilation_db_path, 'r') as fileobj:
+            compilation_db = json.load(fileobj)
     except IOError as why:
         print('Failed to parse JSON compilation database: %s' % why)
         return 1
 
+    compilation_db = fixup_compilation_db(compilation_db)
     compilation_db = slice_compilation_db(compilation_db, source_files)
 
     # Transform compilation db entries into a list of IWYU invocations.
diff --git a/iwyu_tool_test.py b/iwyu_tool_test.py
index c9b3ddd..2d2f0a9 100755
--- a/iwyu_tool_test.py
+++ b/iwyu_tool_test.py
@@ -8,6 +8,7 @@
 # License. See LICENSE.TXT for details.
 #
 ##===----------------------------------------------------------------------===##
+import os
 import sys
 import time
 import random
@@ -272,5 +273,25 @@ class BootstrapTests(unittest.TestCase):
                          self.main.call_args['extra_args'])
 
 
+class CompilationDBTests(unittest.TestCase):
+    def setUp(self):
+        self.cwd = os.path.realpath(os.getcwd())
+
+    def test_fixup_compilation_db(self):
+        """ Compilation database path canonicalization. """
+        compilation_db = [
+            {
+                "directory": "/home/user/llvm/build/test",
+                "file": "Test.cpp"
+            }
+        ]
+
+        canonical = iwyu_tool.fixup_compilation_db(compilation_db)
+
+        # Check that file path is made absolute.
+        entry = canonical[0]
+        self.assertEqual(os.path.join(self.cwd, 'Test.cpp'), entry['file'])
+
+
 if __name__ == '__main__':
     unittest.main()