From 8a1ce0faed1e8e15d2bb6a266c9f5fa71ed5e2d7 2020-02-27 17:53:21
From: Matthias Bussonnier <bussonniermatthias@gmail.com>
Date: 2020-02-27 17:53:21
Subject: [PATCH] Merge pull request #12144 from meeseeksmachine/auto-backport-of-pr-12130-on-7.x

Backport PR #12130 on branch 7.x (Ensure set_custom_completer is working. Fixes #11272)
---

diff --git a/.travis.yml b/.travis.yml
index a70f00a..9bb3a9b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -72,7 +72,7 @@ matrix:
     - arch: arm64
       python: "3.7"
       dist: xenial
-      env: ARM64=True
+      env: ARM64=True IPYTHON_TESTING_TIMEOUT_SCALE=2
       sudo: true
     - arch: amd64
       python: "3.8-dev"
diff --git a/IPython/core/completer.py b/IPython/core/completer.py
index 0942798..9a81d63 100644
--- a/IPython/core/completer.py
+++ b/IPython/core/completer.py
@@ -626,6 +626,8 @@ class Completer(Configurable):
         else:
             self.global_namespace = global_namespace
 
+        self.custom_matchers = []
+
         super(Completer, self).__init__(**kwargs)
 
     def complete(self, text, state):
@@ -1122,12 +1124,14 @@ class IPCompleter(Completer):
 
         if self.use_jedi:
             return [
+                *self.custom_matchers,
                 self.file_matches,
                 self.magic_matches,
                 self.dict_key_matches,
             ]
         else:
             return [
+                *self.custom_matchers,
                 self.python_matches,
                 self.file_matches,
                 self.magic_matches,
diff --git a/IPython/core/interactiveshell.py b/IPython/core/interactiveshell.py
index 4cbc885..848a14a 100644
--- a/IPython/core/interactiveshell.py
+++ b/IPython/core/interactiveshell.py
@@ -2218,7 +2218,7 @@ class InteractiveShell(SingletonConfigurable):
         list where you want the completer to be inserted."""
 
         newcomp = types.MethodType(completer,self.Completer)
-        self.Completer.matchers.insert(pos,newcomp)
+        self.Completer.custom_matchers.insert(pos,newcomp)
 
     def set_completer_frame(self, frame=None):
         """Set the frame of the completer."""
diff --git a/IPython/core/tests/test_interactiveshell.py b/IPython/core/tests/test_interactiveshell.py
index 578ef27..496e3bd 100644
--- a/IPython/core/tests/test_interactiveshell.py
+++ b/IPython/core/tests/test_interactiveshell.py
@@ -998,3 +998,21 @@ def test_should_run_async():
     assert not ip.should_run_async("a = 5")
     assert ip.should_run_async("await x")
     assert ip.should_run_async("import asyncio; await asyncio.sleep(1)")
+
+
+def test_set_custom_completer():
+    num_completers = len(ip.Completer.matchers)
+
+    def foo(*args, **kwargs):
+        return "I'm a completer!"
+
+    ip.set_custom_completer(foo, 0)
+
+    # check that we've really added a new completer
+    assert len(ip.Completer.matchers) == num_completers + 1
+
+    # check that the first completer is the function we defined
+    assert ip.Completer.matchers[0]() == "I'm a completer!"
+
+    # clean up
+    ip.Completer.custom_matchers.pop()