Support MINID and LIMIT on XADD (#1548)

* MINID and LIMIT

redis/commands.py

@@ -1640,24 +1640,40 @@ def xack(self, name, groupname, *ids):
         return self.execute_command('XACK', name, groupname, *ids)
 
     def xadd(self, name, fields, id='*', maxlen=None, approximate=True,
-             nomkstream=False):
+             nomkstream=False, minid=None, limit=None):
         """
         Add to a stream.
         name: name of the stream
         fields: dict of field/value pairs to insert into the stream
         id: Location to insert this record. By default it is appended.
-        maxlen: truncate old stream members beyond this size
+        maxlen: truncate old stream members beyond this size.
+        Can't be specify with minid.
+        minid: the minimum id in the stream to query.
+        Can't be specify with maxlen.
         approximate: actual stream length may be slightly more than maxlen
         nomkstream: When set to true, do not make a stream
+        limit: specifies the maximum number of entries to retrieve
         """
         pieces = []
+        if maxlen is not None and minid is not None:
+            raise DataError("Only one of ```maxlen``` or ```minid```",
+                            "may be specified")
+
         if maxlen is not None:
             if not isinstance(maxlen, int) or maxlen < 1:
                 raise DataError('XADD maxlen must be a positive integer')
             pieces.append(b'MAXLEN')
             if approximate:
                 pieces.append(b'~')
             pieces.append(str(maxlen))
+        if minid is not None:
+            pieces.append(b'MINID')
+            if approximate:
+                pieces.append(b'~')
+            pieces.append(minid)
+        if limit is not None:
+            pieces.append(b"LIMIT")
+            pieces.append(limit)
         if nomkstream:
             pieces.append(b'NOMKSTREAM')
         pieces.append(id)
@@ -2002,7 +2018,7 @@ def xtrim(self, name, maxlen=None, approximate=True, minid=None,
         name: name of the stream.
         maxlen: truncate old stream messages beyond this size
         approximate: actual stream length may be slightly more than maxlen
-        minin: the minimum id in the stream to query
+        minid: the minimum id in the stream to query
         limit: specifies the maximum number of entries to retrieve
         """
         pieces = []

tests/test_commands.py

@@ -2422,6 +2422,56 @@ def test_xadd_nomkstream(self, r):
         r.xadd(stream, {'some': 'other'}, nomkstream=True)
         assert r.xlen(stream) == 3
 
+    @skip_if_server_version_lt('6.2.0')
+    def test_xadd_minlen_and_limit(self, r):
+        stream = 'stream'
+
+        r.xadd(stream, {'foo': 'bar'})
+        r.xadd(stream, {'foo': 'bar'})
+        r.xadd(stream, {'foo': 'bar'})
+        r.xadd(stream, {'foo': 'bar'})
+
+        # Future self: No limits without approximate, according to the api
+        with pytest.raises(redis.ResponseError):
+            assert r.xadd(stream, {'foo': 'bar'}, maxlen=3,
+                          approximate=False, limit=2)
+
+        # limit can not be provided without maxlen or minid
+        with pytest.raises(redis.ResponseError):
+            assert r.xadd(stream, {'foo': 'bar'}, limit=2)
+
+        # maxlen with a limit
+        assert r.xadd(stream, {'foo': 'bar'}, maxlen=3,
+                      approximate=True, limit=2)
+        r.delete(stream)
+
+        # maxlen and minid can not be provided together
+        with pytest.raises(redis.DataError):
+            assert r.xadd(stream, {'foo': 'bar'}, maxlen=3,
+                          minid="sometestvalue")
+
+        # minid with a limit
+        m1 = r.xadd(stream, {'foo': 'bar'})
+        r.xadd(stream, {'foo': 'bar'})
+        r.xadd(stream, {'foo': 'bar'})
+        r.xadd(stream, {'foo': 'bar'})
+        assert r.xadd(stream, {'foo': 'bar'}, approximate=True,
+                      minid=m1, limit=3)
+
+        # pure minid
+        r.xadd(stream, {'foo': 'bar'})
+        r.xadd(stream, {'foo': 'bar'})
+        r.xadd(stream, {'foo': 'bar'})
+        m4 = r.xadd(stream, {'foo': 'bar'})
+        assert r.xadd(stream, {'foo': 'bar'}, approximate=False, minid=m4)
+
+        # minid approximate
+        r.xadd(stream, {'foo': 'bar'})
+        r.xadd(stream, {'foo': 'bar'})
+        m3 = r.xadd(stream, {'foo': 'bar'})
+        r.xadd(stream, {'foo': 'bar'})
+        assert r.xadd(stream, {'foo': 'bar'}, approximate=True, minid=m3)
+
     @skip_if_server_version_lt('6.2.0')
     def test_xautoclaim(self, r):
         stream = 'stream'