Show the mnemonic of pytest.ExitCode in RunResult's repr

Fix #4901

Author: nicoddemus

changelog/4901.trivial.rst

@@ -0,0 +1,2 @@
+``RunResult`` from ``pytester`` now displays the mnemonic of the ``ret`` attribute when it is a
+valid ``pytest.ExitCode`` value.

src/_pytest/pytester.py

@@ -362,7 +362,10 @@ class RunResult:
     """
 
     def __init__(self, ret, outlines, errlines, duration):
-        self.ret = ret
+        try:
+            self.ret = pytest.ExitCode(ret)
+        except ValueError:
+            self.ret = ret
         self.outlines = outlines
         self.errlines = errlines
         self.stdout = LineMatcher(outlines)
@@ -371,7 +374,7 @@ def __init__(self, ret, outlines, errlines, duration):
 
     def __repr__(self):
         return (
-            "<RunResult ret=%r len(stdout.lines)=%d len(stderr.lines)=%d duration=%.2fs>"
+            "<RunResult ret=%s len(stdout.lines)=%d len(stderr.lines)=%d duration=%.2fs>"
             % (self.ret, len(self.stdout.lines), len(self.stderr.lines), self.duration)
         )
 

testing/test_pytester.py

@@ -616,3 +616,22 @@ def test():
     child = testdir.spawn_pytest(str(p1))
     out = child.read()
     assert child.wait() == 0, out.decode("utf8")
+
+
+def test_run_result_repr():
+    outlines = [""] * 3
+    errlines = [""] * 4
+
+    # known exit code
+    r = pytester.RunResult(1, outlines, errlines, duration=0.5)
+    assert (
+        repr(r) == "<RunResult ret=ExitCode.TESTS_FAILED len(stdout.lines)=3"
+        " len(stderr.lines)=4 duration=0.50s>"
+    )
+
+    # unknown exit code: just the number
+    r = pytester.RunResult(99, outlines, errlines, duration=0.5)
+    assert (
+        repr(r) == "<RunResult ret=99 len(stdout.lines)=3"
+        " len(stderr.lines)=4 duration=0.50s>"
+    )