Utils fixes + add missing test coverage

Make a few changes to utils usage to make them more testable and have
better APIs, and add missing test coverage for this module.

Fix a couple of edge cases with the pretty file size util discovered by
unit tests

Add nosetests and coverage config to simplify build script, and omit
cli.py for now pending issue #13.

.coveragerc

@@ -0,0 +1,2 @@
+[report]
+omit = s3_browser/cli.py

build.sh

@@ -27,12 +27,6 @@ echo -n "$RESET"
 
 echo ''
 
-nosetests \
-  --with-coverage \
-  --cover-package s3_browser \
-  --cover-inclusive \
-  --cover-html \
-  --cover-min-percentage 85 \
-  --cover-html-dir build/coverage || exit 1
+nosetests --with-coverage || exit 1
 
 exit $EXIT_CODE

s3_browser/tests/test_utils.py

@@ -0,0 +1,65 @@
+import datetime
+import unittest
+
+from s3_browser import utils
+
+
+class UtilsTest(unittest.TestCase):
+    def test_pretty_size(self):
+        """Test that the pretty-size util approximates filesizes correctly"""
+        cases = [
+            (0, '0 B'),
+            (233, '233 B'),
+            (1023, '1023 B'),
+            (1024, '1 KB'),
+            (1024 ** 2 - 1, '1 MB'),
+            (12345678, '12 MB'),
+            (1024 ** 3 + 100, '1 GB'),
+            (1024 ** 4 + 1, '1 TB'),
+            (1024 ** 5 * 2, '2048 TB'),
+        ]
+
+        for v, expected in cases:
+            actual = utils.pretty_size(v)
+            self.assertEqual(actual, expected)
+
+    def test_strip_s3_metadata(self):
+        """Test that full s3 metadata is correctly stripped to essentials"""
+
+        # Anonymised sample response from a head_object call with boto3
+        data = {
+            'ResponseMetadata': {
+                'RequestId': 'XXXXXXXXXXXXXXXX',
+                'HostId': 'hhhhhhhhhhhhhhhhhhhhhhhhhh',
+                'HTTPStatusCode': 200,
+                'HTTPHeaders': {
+                    'x-amz-id-2': 'ababababababababaabababababab',
+                    'x-amz-request-id': 'XXXXXXXXXXXXXXXX',
+                    'date': 'Wed, 20 Oct 2021 00:00:00 GMT',
+                    'last-modified': 'Fri, 22 May 2021 00:00:00 GMT',
+                    'etag': '"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"',
+                    'accept-ranges': 'bytes',
+                    'content-type': 'application/json',
+                    'server': 'AmazonS3',
+                    'content-length': '13337'
+                },
+                'RetryAttempts': 0
+            },
+            'AcceptRanges': 'bytes',
+            'LastModified': datetime.datetime(2021, 5, 22, 0, 0, 0),
+            'ContentLength': 13409,
+            'ETag': '"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"',
+            'ContentType': 'application/x-tar',
+            'Metadata': {}
+        }
+
+        expected = {
+            'Content-Length': '13 KB (13337 bytes)',
+            'Content-Type': 'application/json',
+            'Last-Modified': 'Fri, 22 May 2021 00:00:00 GMT',
+            'Metadata': {}
+        }
+
+        actual = utils.strip_s3_metadata(data)
+
+        self.assertEqual(actual, expected)

s3_browser/utils.py

@@ -59,16 +59,16 @@ def _format_key(k):
             print_dict(v, indent_level=indent_level + 1)
 
 
-def _pretty_size(n):
-    """Convert a size in bytes to a human-readable string"""
-    if not n:
-        return None
-
+def pretty_size(n):
+    """
+    Convert a size in bytes to a human-readable string, rounded to nearest
+    whole number of suitable units (B, KB, MB, GB or TB)
+    """
     size = int(n)
     shortened = None
 
     for suffix in ('B', 'KB', 'MB', 'GB', 'TB'):
-        if size < 1024:
+        if size <= 1023 or suffix == 'TB':
             shortened = '{} {}'.format(round(size), suffix)
             break
 
@@ -78,12 +78,12 @@ def _pretty_size(n):
 
 
 def strip_s3_metadata(data):
-    """Strip s3 metadata down to the useful stuff"""
+    """Strip s3 head_object metadata down to the useful stuff"""
     metadata = data.get('Metadata', {})
     http_head = data.get('ResponseMetadata', {}).get('HTTPHeaders', {})
 
-    content_length = http_head.get('content-length')
-    pretty_len = _pretty_size(content_length)
+    content_length = int(http_head.get('content-length') or 0)
+    pretty_len = pretty_size(content_length)
     if pretty_len:
         content_length = '{} ({} bytes)'.format(pretty_len, content_length)
 

setup.cfg

@@ -0,0 +1,6 @@
+[nosetests]
+cover-package=s3_browser
+cover-inclusive=1
+cover-html=1
+cover-min-percentage=75
+cover-html-dir=build/coverage