Improve our own wcwidth implementation and remove dependency on wcwidth package

`TerminalWriter`, imported recently from `py`, contains its own
incomplete wcwidth (`char_with`/`get_line_width`) implementation. The
`TerminalReporter` also needs this, but uses the external `wcwidth`
package.

This commit brings the `TerminalWriter` implementation up-to-par with
`wcwidth`, moves to implementation to a new file `_pytest._io.wcwidth`
which is used everywhere, and removes the dependency.

The differences compared to the `wcwidth` package are:

- Normalizes the string before counting.

- Uses Python's `unicodedata` instead of vendored Unicode tables. This
  means the data corresponds to the Python's version Unicode version
  instead of the `wcwidth`'s package version.

- Apply some optimizations.

1 files changed, 13 insertions, 14 deletions

diff --git a/testing/test_terminal.py b/testing/test_terminal.py
index 0f5b4cb68..17fd29238 100644
--- a/testing/test_terminal.py
+++ b/testing/test_terminal.py
@@ -14,7 +14,9 @@ import pluggy
 import py
 
 import _pytest.config
+import _pytest.terminal
 import pytest
+from _pytest._io.wcwidth import wcswidth
 from _pytest.config import ExitCode
 from _pytest.pytester import Testdir
 from _pytest.reports import BaseReport
@@ -2027,9 +2029,6 @@ def test_skip_reasons_folding():
 
 
 def test_line_with_reprcrash(monkeypatch):
-    import _pytest.terminal
-    from wcwidth import wcswidth
-
     mocked_verbose_word = "FAILED"
 
     mocked_pos = "some::nodeid"
@@ -2079,19 +2078,19 @@ def test_line_with_reprcrash(monkeypatch):
     check("some\nmessage", 80, "FAILED some::nodeid - some")
 
     # Test unicode safety.
-    check("😄😄😄😄😄\n2nd line", 25, "FAILED some::nodeid - ...")
-    check("😄😄😄😄😄\n2nd line", 26, "FAILED some::nodeid - ...")
-    check("😄😄😄😄😄\n2nd line", 27, "FAILED some::nodeid - 😄...")
-    check("😄😄😄😄😄\n2nd line", 28, "FAILED some::nodeid - 😄...")
-    check("😄😄😄😄😄\n2nd line", 29, "FAILED some::nodeid - 😄😄...")
+    check("🉐🉐🉐🉐🉐\n2nd line", 25, "FAILED some::nodeid - ...")
+    check("🉐🉐🉐🉐🉐\n2nd line", 26, "FAILED some::nodeid - ...")
+    check("🉐🉐🉐🉐🉐\n2nd line", 27, "FAILED some::nodeid - 🉐...")
+    check("🉐🉐🉐🉐🉐\n2nd line", 28, "FAILED some::nodeid - 🉐...")
+    check("🉐🉐🉐🉐🉐\n2nd line", 29, "FAILED some::nodeid - 🉐🉐...")
 
     # NOTE: constructed, not sure if this is supported.
-    mocked_pos = "nodeid::😄::withunicode"
-    check("😄😄😄😄😄\n2nd line", 29, "FAILED nodeid::😄::withunicode")
-    check("😄😄😄😄😄\n2nd line", 40, "FAILED nodeid::😄::withunicode - 😄😄...")
-    check("😄😄😄😄😄\n2nd line", 41, "FAILED nodeid::😄::withunicode - 😄😄...")
-    check("😄😄😄😄😄\n2nd line", 42, "FAILED nodeid::😄::withunicode - 😄😄😄...")
-    check("😄😄😄😄😄\n2nd line", 80, "FAILED nodeid::😄::withunicode - 😄😄😄😄😄")
+    mocked_pos = "nodeid::🉐::withunicode"
+    check("🉐🉐🉐🉐🉐\n2nd line", 29, "FAILED nodeid::🉐::withunicode")
+    check("🉐🉐🉐🉐🉐\n2nd line", 40, "FAILED nodeid::🉐::withunicode - 🉐🉐...")
+    check("🉐🉐🉐🉐🉐\n2nd line", 41, "FAILED nodeid::🉐::withunicode - 🉐🉐...")
+    check("🉐🉐🉐🉐🉐\n2nd line", 42, "FAILED nodeid::🉐::withunicode - 🉐🉐🉐...")
+    check("🉐🉐🉐🉐🉐\n2nd line", 80, "FAILED nodeid::🉐::withunicode - 🉐🉐🉐🉐🉐")
 
 
 @pytest.mark.parametrize(