Ensure Result.messages is always unique

5 files changed, 31 insertions, 13 deletions

diff --git a/NEWS b/NEWS
index 795fa30..566c6bc 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,7 @@
+# 0.3.25
+
+* Remove duplicate messages from results.
+
 # 0.3.24
 
 * Continue with warning if external images cannot be found.
diff --git a/mammoth/lists.py b/mammoth/lists.py
index cf39b99..6e39ae0 100644
--- a/mammoth/lists.py
+++ b/mammoth/lists.py
@@ -14,6 +14,15 @@ def _collect(values, result):
         elif value is not None:
             result.append(value)
 
+def unique(values):
+    output = []
+    seen = set()
+    for value in values:
+        if value not in seen:
+            seen.add(value)
+            output.append(value)
+    return output
+
 
 if sys.version_info[0] == 2:
     map = map
diff --git a/mammoth/results.py b/mammoth/results.py
index 9112296..59c3a42 100644
--- a/mammoth/results.py
+++ b/mammoth/results.py
@@ -1,10 +1,12 @@
 import collections
 
+from .lists import unique
+
 
 class Result(object):
     def __init__(self, value, messages):
         self.value = value
-        self.messages = messages
+        self.messages = unique(messages)
     
     def map(self, func):
         return Result(func(self.value), self.messages)
diff --git a/scripts/mammoth b/scripts/mammoth
index be7ad10..f4865fb 100644
--- a/scripts/mammoth
+++ b/scripts/mammoth
@@ -34,24 +34,14 @@ def main():
             convert_image=convert_image,
             output_format=args.output_format,
         )
-        for message in _unique([message.message for message in result.messages]):
-            sys.stderr.write(message)
+        for message in result.messages:
+            sys.stderr.write(message.message)
             sys.stderr.write("\n")
         
         with _open_output(output_path) as output:
             output.write(result.value)
 
 
-def _unique(values):
-    output = []
-    seen = set()
-    for value in values:
-        if value not in seen:
-            seen.add(value)
-            output.append(value)
-    return output
-
-
 class ImageWriter(object):
     def __init__(self, output_dir):
         self._output_dir = output_dir
diff --git a/tests/lists_tests.py b/tests/lists_tests.py
new file mode 100644
index 0000000..49d5331
--- /dev/null
+++ b/tests/lists_tests.py
@@ -0,0 +1,13 @@
+from nose.tools import istest, assert_equal
+
+from mammoth.lists import unique
+
+
+@istest
+def unique_of_empty_list_is_empty_list():
+    assert_equal([], unique([]))
+
+
+@istest
+def unique_removes_duplicates_while_preserving_order():
+    assert_equal(["apple", "banana"], unique(["apple", "banana", "apple"]))