implement __format__ for a more fine grained output of the error (#50)

---------
Co-authored-by: Nicola Coretti <[email protected]>

doc/changes/unreleased.md

@@ -4,3 +4,7 @@
 
 * Relocked Dependencies
 * Update toolbox workflows
+
+## Added
+
+* Added support for finegrained error output control

exasol/error/_error.py

@@ -52,8 +52,45 @@ def build_error(code, msg, mitigations, params):
     def __str__(self) -> str:
         return f"{self._error}"
 
-    # TODO: Implement __format__ to conveniently support long and short reporting format
-    # See also see, Github Issue #28 https://github.com/exasol/error-reporting-python/issues/28
+    def __format__(self, format_spec: str):
+        def _name(error: Error):
+            return f"{error._error._error_code} "
+
+        def _message(error: Error):
+            return f"{error._error._message_builder} "
+
+        def _mitigations(error: Error):
+            return f"{error._error._mitigations} "
+
+        def _parameters(error: Error):
+            return f"{error._error._parameter_dict} "
+
+        def _short(error: Error):
+            return _name(error) + _message(error)
+
+        def _long(error: Error):
+            return (
+                _name(error)
+                + _message(error)
+                + _mitigations(error)
+                + _parameters(error)
+            )
+
+        output = ""
+        formats = {
+            "name": _name(self),
+            "message": _message(self),
+            "mitigations": _mitigations(self),
+            "parameters": _parameters(self),
+            "short": _short(self),
+            "long": _long(self),
+            "": "",
+        }
+        for part in format_spec.split(" "):
+            if part in formats:
+                output += formats[part]
+
+        return output[:-1]
 
 
 # ATTENTION: In the event of an exception while creating an error, we encounter a chicken-and-egg problem regarding error definitions.

test/unit/fmt_test.py

@@ -0,0 +1,131 @@
+import pytest
+
+from exasol.error._error import Error
+
+
+@pytest.mark.parametrize(
+    "error, fmt, expected",
+    [
+        (
+            Error(
+                code="E-TEST-1",
+                message="Not enough space on device {/dev/sda1}.",
+                mitigations=[
+                    "Delete something from {/dev/sda1}",
+                    "Create larger partition.",
+                ],
+                parameters={"device": "/dev/sda1"},
+            ),
+            "",
+            "",
+        ),
+        (
+            Error(
+                code="E-TEST-1",
+                message="Not enough space on device {/dev/sda1}.",
+                mitigations=[
+                    "Delete something from {/dev/sda1}",
+                    "Create larger partition.",
+                ],
+                parameters={"device": "/dev/sda1"},
+            ),
+            "unknown",
+            "",
+        ),
+        (
+            Error(
+                code="E-TEST-1",
+                message="Not enough space on device {/dev/sda1}.",
+                mitigations=[
+                    "Delete something from {/dev/sda1}",
+                    "Create larger partition.",
+                ],
+                parameters={"device": "/dev/sda1"},
+            ),
+            "long",
+            "E-TEST-1 ['Not enough space on device {/dev/sda1}.'] ['Delete something from {/dev/sda1}', 'Create larger partition.'] {'device': '/dev/sda1'}",
+        ),
+        (
+            Error(
+                code="E-TEST-1",
+                message="Not enough space on device {/dev/sda1}.",
+                mitigations=[
+                    "Delete something from {/dev/sda1}",
+                    "Create larger partition.",
+                ],
+                parameters={"device": "/dev/sda1"},
+            ),
+            "short",
+            "E-TEST-1 ['Not enough space on device {/dev/sda1}.']",
+        ),
+        (
+            Error(
+                code="E-TEST-1",
+                message="Not enough space on device {/dev/sda1}.",
+                mitigations=[
+                    "Delete something from {/dev/sda1}",
+                    "Create larger partition.",
+                ],
+                parameters={"device": "/dev/sda1"},
+            ),
+            "name",
+            "E-TEST-1",
+        ),
+        (
+            Error(
+                code="E-TEST-1",
+                message="Not enough space on device {/dev/sda1}.",
+                mitigations=[
+                    "Delete something from {/dev/sda1}",
+                    "Create larger partition.",
+                ],
+                parameters={"device": "/dev/sda1"},
+            ),
+            "message",
+            "['Not enough space on device {/dev/sda1}.']",
+        ),
+        (
+            Error(
+                code="E-TEST-1",
+                message="Not enough space on device {/dev/sda1}.",
+                mitigations=[
+                    "Delete something from {/dev/sda1}",
+                    "Create larger partition.",
+                ],
+                parameters={"device": "/dev/sda1"},
+            ),
+            "mitigations",
+            "['Delete something from {/dev/sda1}', 'Create larger partition.']",
+        ),
+        (
+            Error(
+                code="E-TEST-1",
+                message="Not enough space on device {/dev/sda1}.",
+                mitigations=[
+                    "Delete something from {/dev/sda1}",
+                    "Create larger partition.",
+                ],
+                parameters={"device": "/dev/sda1"},
+            ),
+            "parameters",
+            "{'device': '/dev/sda1'}",
+        ),
+        (
+            Error(
+                code="E-TEST-1",
+                message="Not enough space on device {/dev/sda1}.",
+                mitigations=[
+                    "Delete something from {/dev/sda1}",
+                    "Create larger partition.",
+                ],
+                parameters={"device": "/dev/sda1"},
+            ),
+            "parameters mitigations message name",
+            "{'device': '/dev/sda1'} ['Delete something from {/dev/sda1}', 'Create larger partition.'] ['Not enough space on device {/dev/sda1}.'] E-TEST-1",
+        ),
+    ],
+)
+def test_fmt(error, fmt, expected):
+    fmt_str = f"{{error:{fmt}}}"
+    actual = fmt_str.format(error=error)
+    assert actual == expected