Make pygments dependency required

Closes #7683

Author: The-Compiler

changelog/7683.improvement.rst

@@ -0,0 +1 @@
+The formerly optional ``pygments`` dependency is now required, causing output always to be source-highlighted (unless disabled via the ``--code-highlight=no`` CLI option).

pyproject.toml

@@ -51,14 +51,14 @@ dependencies = [
     "iniconfig",
     "packaging",
     "pluggy>=1.5,<2",
+    "pygments>=2.7.2",
     "tomli>=1; python_version<'3.11'",
 ]
 optional-dependencies.dev = [
     "argcomplete",
     "attrs>=19.2",
     "hypothesis>=3.56",
     "mock",
-    "pygments>=2.7.2",
     "requests",
     "setuptools",
     "xmlschema",

src/_pytest/_io/terminalwriter.py

@@ -9,17 +9,17 @@
 from typing import final
 from typing import Literal
 from typing import TextIO
-from typing import TYPE_CHECKING
+
+import pygments
+from pygments.formatters.terminal import TerminalFormatter
+from pygments.lexer import Lexer
+from pygments.lexers.diff import DiffLexer
+from pygments.lexers.python import PythonLexer
 
 from ..compat import assert_never
 from .wcwidth import wcswidth
 
 
-if TYPE_CHECKING:
-    from pygments.formatter import Formatter
-    from pygments.lexer import Lexer
-
-
 # This code was initially copied from py 1.8.1, file _io/terminalwriter.py.
 
 
@@ -201,37 +201,22 @@ def _write_source(self, lines: Sequence[str], indents: Sequence[str] = ()) -> No
         for indent, new_line in zip(indents, new_lines):
             self.line(indent + new_line)
 
-    def _get_pygments_lexer(self, lexer: Literal["python", "diff"]) -> Lexer | None:
-        try:
-            if lexer == "python":
-                from pygments.lexers.python import PythonLexer
-
-                return PythonLexer()
-            elif lexer == "diff":
-                from pygments.lexers.diff import DiffLexer
-
-                return DiffLexer()
-            else:
-                assert_never(lexer)
-        except ModuleNotFoundError:
-            return None
-
-    def _get_pygments_formatter(self) -> Formatter | None:
-        try:
-            import pygments.util
-        except ModuleNotFoundError:
-            return None
+    def _get_pygments_lexer(self, lexer: Literal["python", "diff"]) -> Lexer:
+        if lexer == "python":
+            return PythonLexer()
+        elif lexer == "diff":
+            return DiffLexer()
+        else:
+            assert_never(lexer)
 
+    def _get_pygments_formatter(self) -> TerminalFormatter:
         from _pytest.config.exceptions import UsageError
 
         theme = os.getenv("PYTEST_THEME")
         theme_mode = os.getenv("PYTEST_THEME_MODE", "dark")
 
         try:
-            from pygments.formatters.terminal import TerminalFormatter
-
             return TerminalFormatter(bg=theme_mode, style=theme)
-
         except pygments.util.ClassNotFound as e:
             raise UsageError(
                 f"PYTEST_THEME environment variable has an invalid value: '{theme}'. "
@@ -251,16 +236,11 @@ def _highlight(
             return source
 
         pygments_lexer = self._get_pygments_lexer(lexer)
-        if pygments_lexer is None:
-            return source
-
         pygments_formatter = self._get_pygments_formatter()
-        if pygments_formatter is None:
-            return source
-
-        from pygments import highlight
 
-        highlighted: str = highlight(source, pygments_lexer, pygments_formatter)
+        highlighted: str = pygments.highlight(
+            source, pygments_lexer, pygments_formatter
+        )
         # pygments terminal formatter may add a newline when there wasn't one.
         # We don't want this, remove.
         if highlighted[-1] == "\n" and source[-1] != "\n":