code: do not truncate args in output when running with -vvv

AUTHORS

@@ -276,6 +276,7 @@ Michael Droettboom
 Michael Goerz
 Michael Krebs
 Michael Seifert
+Michael Vogt
 Michal Wajszczuk
 Michał Górny
 Michał Zięba

changelog/2871.improvement.rst

@@ -0,0 +1,37 @@
+Do not truncate the args in output when running with `-vvv`
+
+Sometimes it is useful to get the untruncated arguments as part of the
+pytest output. This can be useful when using e.g. `subprocess.run()`
+and `capture_output=True`. When passing `-vvv` the full content of
+`stdout` is then available as part of the `pytest -vvv` output, e.g.
+
+```python
+def test_vvv():
+    subprocess.run(
+        ["sh", "-c", "seq 400|xargs echo; false"],
+        capture_output=True,
+        text=True,
+        encoding="utf8",
+        check=True,
+    )
+```
+
+will now output:
+```
+$ pytest -vvv
+=================================== FAILURES ===================================
+___________________________________ test_vvv ___________________________________
+
+    def test_vvv():
+>      subprocess.run(["sh","-c","seq 400|xargs echo; false"], capture_output=True, text=True, encoding="utf8", check=True)
+
+test_full_output_vvv.py:3:
+_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
+
+input = None, capture_output = True, timeout = None, check = True
+popenargs = (['sh', '-c', 'seq 400|xargs echo; false'],)
+kwargs = {'encoding': 'utf8', 'stderr': -1, 'stdout': -1, 'text': True}
+process = <Popen: returncode: 1 args: ['sh', '-c', 'seq 400|xargs echo; false']>
+stdout = '1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400\n'
+...
+```

src/_pytest/_code/code.py

@@ -636,6 +636,7 @@
         ] = True,
         funcargs: bool = False,
         truncate_locals: bool = True,
+        truncate_args: bool = True,
         chain: bool = True,
     ) -> Union["ReprExceptionInfo", "ExceptionChainRepr"]:
         """Return str()able representation of this exception info.
@@ -666,6 +667,9 @@
         :param bool truncate_locals:
             With ``showlocals==True``, make sure locals can be safely represented as strings.
 
+        :param bool truncate_args:
+            With ``showargs==True``, make sure args can be safely represented as strings.
+
         :param bool chain:
             If chained exceptions in Python 3 should be shown.
 
@@ -692,6 +696,7 @@
             tbfilter=tbfilter,
             funcargs=funcargs,
             truncate_locals=truncate_locals,
+            truncate_args=truncate_args,
             chain=chain,
         )
         return fmt.repr_excinfo(self)
@@ -810,6 +815,7 @@
     tbfilter: Union[bool, Callable[[ExceptionInfo[BaseException]], Traceback]] = True
     funcargs: bool = False
     truncate_locals: bool = True
+    truncate_args: bool = True
     chain: bool = True
     astcache: Dict[Union[str, Path], ast.AST] = dataclasses.field(
         default_factory=dict, init=False, repr=False
@@ -840,7 +846,11 @@
         if self.funcargs:
             args = []
             for argname, argvalue in entry.frame.getargs(var=True):
-                args.append((argname, saferepr(argvalue)))
+                if self.truncate_args:
+                    str_repr = saferepr(argvalue)
+                else:
+                    str_repr = saferepr(argvalue, maxsize=None)
+                args.append((argname, str_repr))
             return ReprFuncArgs(args)
         return None
 

src/_pytest/nodes.py

@@ -448,6 +448,8 @@ def _repr_failure_py(
         else:
             truncate_locals = True
 
+        truncate_args = False if self.config.getoption("verbose", 0) > 2 else True
+
         # excinfo.getrepr() formats paths relative to the CWD if `abspath` is False.
         # It is possible for a fixture/test to change the CWD while this code runs, which
         # would then result in the user seeing confusing paths in the failure message.
@@ -466,6 +468,7 @@ def _repr_failure_py(
             style=style,
             tbfilter=tbfilter,
             truncate_locals=truncate_locals,
+            truncate_args=truncate_args,
         )
 
     def repr_failure(

testing/code/test_excinfo.py

@@ -10,6 +10,7 @@
 import sys
 import textwrap
 from typing import Any
+from typing import cast
 from typing import TYPE_CHECKING
 
 import _pytest._code
@@ -708,6 +709,29 @@ def test_repr_local_truncated(self) -> None:
         assert full_reprlocals.lines
         assert full_reprlocals.lines[0] == "l          = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]"
 
+    def test_repr_args_not_truncated(self, importasmod) -> None:
+        mod = importasmod(
+            """
+            def func1(m):
+                raise ValueError("hello\\nworld")
+        """
+        )
+        excinfo = pytest.raises(ValueError, mod.func1, "m" * 500)
+        excinfo.traceback = excinfo.traceback.filter(excinfo)
+        entry = excinfo.traceback[-1]
+        p = FormattedExcinfo(funcargs=True, truncate_args=True)
+        reprfuncargs = p.repr_args(entry)
+        assert reprfuncargs is not None
+        arg1 = cast(str, reprfuncargs.args[0][1])
+        assert len(arg1) < 500
+        assert "..." in arg1
+        # again without truncate
+        p = FormattedExcinfo(funcargs=True, truncate_args=False)
+        reprfuncargs = p.repr_args(entry)
+        assert reprfuncargs is not None
+        assert reprfuncargs.args[0] == ("m", repr("m" * 500))
+        assert "..." not in cast(str, reprfuncargs.args[0][1])
+
     def test_repr_tracebackentry_lines(self, importasmod) -> None:
         mod = importasmod(
             """

testing/test_assertion.py

@@ -2045,3 +2045,36 @@ def test_long_text_fail():
             f"E       AssertionError: assert 'hello world' in '{long_text}'",
         ]
     )
+
+
+def test_full_output_vvv(pytester: Pytester) -> None:
+    pytester.makepyfile(
+        r"""
+        def crash_helper(m):
+            assert 1 == 2
+        def test_vvv():
+            crash_helper(500 * "a")
+    """
+    )
+    result = pytester.runpytest("")
+    # without -vvv, the passed args are truncated
+    expected_non_vvv_arg_line = "m = 'aaaaaaaaaaaaaaa*..aaaaaaaaaaaa*"
+    result.stdout.fnmatch_lines(
+        [
+            expected_non_vvv_arg_line,
+            "test_full_output_vvv.py:2: AssertionError",
+        ],
+    )
+    # double check that the untruncated part is not in the output
+    expected_vvv_arg_line = "m = '{}'".format(500 * "a")
+    result.stdout.no_fnmatch_line(expected_vvv_arg_line)
+
+    # but with "-vvv" the args are not truncated
+    result = pytester.runpytest("-vvv")
+    result.stdout.fnmatch_lines(
+        [
+            expected_vvv_arg_line,
+            "test_full_output_vvv.py:2: AssertionError",
+        ]
+    )
+    result.stdout.no_fnmatch_line(expected_non_vvv_arg_line)