Fix issues with CliRunner's echo_stdin

CHANGES.rst

@@ -208,6 +208,8 @@ Unreleased
     :issue:`1568`
 -   The ``MultiCommand.resultcallback`` decorator is renamed to
     ``result_callback``. The old name is deprecated. :issue:`1160`
+-   Fix issues with ``CliRunner`` output when using ``echo_stdin=True``.
+    :issue:`1101`
 
 
 Version 7.1.2

src/click/testing.py

@@ -16,17 +16,23 @@ class EchoingStdin:
     def __init__(self, input, output):
         self._input = input
         self._output = output
+        self._paused = False
 
     def __getattr__(self, x):
         return getattr(self._input, x)
 
     def _echo(self, rv):
-        self._output.write(rv)
+        if not self._paused:
+            self._output.write(rv)
+
         return rv
 
     def read(self, n=-1):
         return self._echo(self._input.read(n))
 
+    def read1(self, n=-1):
+        return self._echo(self._input.read1(n))
+
     def readline(self, n=-1):
         return self._echo(self._input.readline(n))
 
@@ -40,6 +46,16 @@ def __repr__(self):
         return repr(self._input)
 
 
+@contextlib.contextmanager
+def _pause_echo(stream):
+    if stream is None:
+        yield
+    else:
+        stream._paused = True
+        yield
+        stream._paused = False
+
+
 class _NamedTextIOWrapper(io.TextIOWrapper):
     def __init__(self, buffer, name=None, mode=None, **kwargs):
         super().__init__(buffer, **kwargs)
@@ -191,6 +207,7 @@ def isolation(self, input=None, env=None, color=False):
             Added the ``color`` parameter.
         """
         input = make_input_stream(input, self.charset)
+        echo_input = None
 
         old_stdin = sys.stdin
         old_stdout = sys.stdout
@@ -203,11 +220,17 @@ def isolation(self, input=None, env=None, color=False):
         bytes_output = io.BytesIO()
 
         if self.echo_stdin:
-            input = EchoingStdin(input, bytes_output)
+            input = echo_input = EchoingStdin(input, bytes_output)
 
         sys.stdin = input = _NamedTextIOWrapper(
             input, encoding=self.charset, name="<stdin>", mode="r"
         )
+
+        if self.echo_stdin:
+            # Force unbuffered reads, otherwise TextIOWrapper reads a
+            # large chunk which is echoed early.
+            input._CHUNK_SIZE = 1
+
         sys.stdout = _NamedTextIOWrapper(
             bytes_output, encoding=self.charset, name="<stdout>", mode="w"
         )
@@ -225,23 +248,28 @@ def isolation(self, input=None, env=None, color=False):
                 errors="backslashreplace",
             )
 
+        @_pause_echo(echo_input)
         def visible_input(prompt=None):
             sys.stdout.write(prompt or "")
             val = input.readline().rstrip("\r\n")
             sys.stdout.write(f"{val}\n")
             sys.stdout.flush()
             return val
 
+        @_pause_echo(echo_input)
         def hidden_input(prompt=None):
             sys.stdout.write(f"{prompt or ''}\n")
             sys.stdout.flush()
             return input.readline().rstrip("\r\n")
 
+        @_pause_echo(echo_input)
         def _getchar(echo):
             char = sys.stdin.read(1)
+
             if echo:
                 sys.stdout.write(char)
-                sys.stdout.flush()
+
+            sys.stdout.flush()
             return char
 
         default_color = color

tests/test_testing.py

@@ -26,12 +26,65 @@ def test():
     assert not result.exception
     assert result.output == "Hello World!\n"
 
+
+def test_echo_stdin_stream():
+    @click.command()
+    def test():
+        i = click.get_binary_stream("stdin")
+        o = click.get_binary_stream("stdout")
+        while 1:
+            chunk = i.read(4096)
+            if not chunk:
+                break
+            o.write(chunk)
+            o.flush()
+
     runner = CliRunner(echo_stdin=True)
     result = runner.invoke(test, input="Hello World!\n")
     assert not result.exception
     assert result.output == "Hello World!\nHello World!\n"
 
 
+def test_echo_stdin_prompts():
+    @click.command()
+    def test_python_input():
+        foo = input("Foo: ")
+        click.echo(f"foo={foo}")
+
+    runner = CliRunner(echo_stdin=True)
+    result = runner.invoke(test_python_input, input="bar bar\n")
+    assert not result.exception
+    assert result.output == "Foo: bar bar\nfoo=bar bar\n"
+
+    @click.command()
+    @click.option("--foo", prompt=True)
+    def test_prompt(foo):
+        click.echo(f"foo={foo}")
+
+    result = runner.invoke(test_prompt, input="bar bar\n")
+    assert not result.exception
+    assert result.output == "Foo: bar bar\nfoo=bar bar\n"
+
+    @click.command()
+    @click.option("--foo", prompt=True, hide_input=True)
+    def test_hidden_prompt(foo):
+        click.echo(f"foo={foo}")
+
+    result = runner.invoke(test_hidden_prompt, input="bar bar\n")
+    assert not result.exception
+    assert result.output == "Foo: \nfoo=bar bar\n"
+
+    @click.command()
+    @click.option("--foo", prompt=True)
+    @click.option("--bar", prompt=True)
+    def test_multiple_prompts(foo, bar):
+        click.echo(f"foo={foo}, bar={bar}")
+
+    result = runner.invoke(test_multiple_prompts, input="one\ntwo\n")
+    assert not result.exception
+    assert result.output == "Foo: one\nBar: two\nfoo=one, bar=two\n"
+
+
 def test_runner_with_stream():
     @click.command()
     def test():
@@ -87,6 +140,25 @@ def continue_it():
     assert not result.exception
     assert result.output == "y\n"
 
+    runner = CliRunner(echo_stdin=True)
+    result = runner.invoke(continue_it, input="y")
+    assert not result.exception
+    assert result.output == "y\n"
+
+    @click.command()
+    def getchar_echo():
+        click.echo(click.getchar(echo=True))
+
+    runner = CliRunner()
+    result = runner.invoke(getchar_echo, input="y")
+    assert not result.exception
+    assert result.output == "yy\n"
+
+    runner = CliRunner(echo_stdin=True)
+    result = runner.invoke(getchar_echo, input="y")
+    assert not result.exception
+    assert result.output == "yy\n"
+
 
 def test_catch_exceptions():
     class CustomError(Exception):