[Frontend] Make tests toml-schema independent (#712)

**Context:** Transition to the quantum device config schema 2

**Description of the Change:** Solve a regarding toml schema 2 udpate in
tests by switching our test custom devices from toml text manipulations
to the device capability manipulations

**Benefits:** 
* Tests no longer require toml text manipulations.
* Tests now contain simple examples of custom devices.
* toml-specific code is now locates in `catalyst.utils.toml`. 

**Possible Drawbacks:**

**Related GitHub Issues:**
PennyLaneAI/pennylane-lightning#642

---------

Co-authored-by: David Ittah <dime10@users.noreply.github.com>

doc/changelog.md

@@ -92,11 +92,14 @@
   annotations.
   [(#751)](https://github.com/PennyLaneAI/catalyst/pull/751)
 
-* Refactored `vmap` decorator in order to follow a unified pattern that uses a callable 
-  class that implements the decorator's logic. This prevents having to excessively define 
+* Refactored `vmap` decorator in order to follow a unified pattern that uses a callable
+  class that implements the decorator's logic. This prevents having to excessively define
   functions in a nested fashion.
   [(#758)](https://github.com/PennyLaneAI/catalyst/pull/758)
 
+* Catalyst tests now manipulate device capabilities rather than text configurations files.
+  [(#712)](https://github.com/PennyLaneAI/catalyst/pull/712)
+
 <h3>Breaking changes</h3>
 
 * Binary distributions for Linux are now based on `manylinux_2_28` instead of `manylinux_2014`.
@@ -198,11 +201,12 @@
 This release contains contributions from (in alphabetical order):
 
 David Ittah,
-Mehrdad Malekmohammadi,
 Erick Ochoa,
+Haochen Paul Wang,
 Lee James O'Riordan,
+Mehrdad Malekmohammadi,
 Raul Torres,
-Haochen Paul Wang.
+Sergei Mironov.
 
 # Release 0.6.0
 

frontend/catalyst/compiler.py

@@ -33,7 +33,7 @@
 
 from catalyst.utils.exceptions import CompileError
 from catalyst.utils.filesystem import Directory
-from catalyst.utils.runtime import get_lib_path
+from catalyst.utils.runtime_environment import get_lib_path
 
 package_root = os.path.dirname(__file__)
 

frontend/catalyst/device/__init__.py

@@ -16,9 +16,18 @@
 Internal API for the device module.
 """
 
-from catalyst.device.qjit_device import QJITDevice, QJITDeviceNewAPI
+from catalyst.device.qjit_device import (
+    BackendInfo,
+    QJITDevice,
+    QJITDeviceNewAPI,
+    extract_backend_info,
+    validate_device_capabilities,
+)
 
 __all__ = (
     "QJITDevice",
     "QJITDeviceNewAPI",
+    "BackendInfo",
+    "extract_backend_info",
+    "validate_device_capabilities",
 )

frontend/catalyst/device/qjit_device.py

@@ -16,10 +16,14 @@
 This module contains device stubs for the old and new PennyLane device API, which facilitate
 the application of decomposition and other device pre-processing routines.
 """
-
+import os
+import pathlib
+import platform
+import re
 from copy import deepcopy
+from dataclasses import dataclass
 from functools import partial
-from typing import Optional, Set
+from typing import Any, Dict, Optional, Set
 
 import pennylane as qml
 from pennylane.measurements import MidMeasureMP
@@ -32,13 +36,10 @@
 )
 from catalyst.utils.exceptions import CompileError
 from catalyst.utils.patching import Patcher
-from catalyst.utils.runtime import BackendInfo, device_get_toml_config
+from catalyst.utils.runtime_environment import get_lib_path
 from catalyst.utils.toml import (
     DeviceCapabilities,
     OperationProperties,
-    ProgramFeatures,
-    TOMLDocument,
-    get_device_capabilities,
     intersect_operations,
     pennylane_operation_set,
 )
@@ -84,6 +85,87 @@
     for op in RUNTIME_OPERATIONS
 }
 
+# TODO: This should be removed after implementing `get_c_interface`
+# for the following backend devices:
+SUPPORTED_RT_DEVICES = {
+    "lightning.qubit": ("LightningSimulator", "librtd_lightning"),
+    "lightning.kokkos": ("LightningKokkosSimulator", "librtd_lightning"),
+    "braket.aws.qubit": ("OpenQasmDevice", "librtd_openqasm"),
+    "braket.local.qubit": ("OpenQasmDevice", "librtd_openqasm"),
+}
+
+
+@dataclass
+class BackendInfo:
+    """Backend information"""
+
+    device_name: str
+    c_interface_name: str
+    lpath: str
+    kwargs: Dict[str, Any]
+
+
+def extract_backend_info(device: qml.QubitDevice, capabilities: DeviceCapabilities) -> BackendInfo:
+    """Extract the backend info from a quantum device. The device is expected to carry a reference
+    to a valid TOML config file."""
+    # pylint: disable=too-many-branches
+
+    dname = device.name
+    if isinstance(device, qml.Device):
+        dname = device.short_name
+
+    device_name = ""
+    device_lpath = ""
+    device_kwargs = {}
+
+    if dname in SUPPORTED_RT_DEVICES:
+        # Support backend devices without `get_c_interface`
+        device_name = SUPPORTED_RT_DEVICES[dname][0]
+        device_lpath = get_lib_path("runtime", "RUNTIME_LIB_DIR")
+        sys_platform = platform.system()
+
+        if sys_platform == "Linux":
+            device_lpath = os.path.join(device_lpath, SUPPORTED_RT_DEVICES[dname][1] + ".so")
+        elif sys_platform == "Darwin":  # pragma: no cover
+            device_lpath = os.path.join(device_lpath, SUPPORTED_RT_DEVICES[dname][1] + ".dylib")
+        else:  # pragma: no cover
+            raise NotImplementedError(f"Platform not supported: {sys_platform}")
+    elif hasattr(device, "get_c_interface"):
+        # Support third party devices with `get_c_interface`
+        device_name, device_lpath = device.get_c_interface()
+    else:
+        raise CompileError(f"The {dname} device does not provide C interface for compilation.")
+
+    if not pathlib.Path(device_lpath).is_file():
+        raise CompileError(f"Device at {device_lpath} cannot be found!")
+
+    if hasattr(device, "shots"):
+        if isinstance(device, qml.Device):
+            device_kwargs["shots"] = device.shots if device.shots else 0
+        else:
+            # TODO: support shot vectors
+            device_kwargs["shots"] = device.shots.total_shots if device.shots else 0
+
+    if dname == "braket.local.qubit":  # pragma: no cover
+        device_kwargs["device_type"] = dname
+        device_kwargs["backend"] = (
+            # pylint: disable=protected-access
+            device._device._delegate.DEVICE_ID
+        )
+    elif dname == "braket.aws.qubit":  # pragma: no cover
+        device_kwargs["device_type"] = dname
+        device_kwargs["device_arn"] = device._device._arn  # pylint: disable=protected-access
+        if device._s3_folder:  # pylint: disable=protected-access
+            device_kwargs["s3_destination_folder"] = str(
+                device._s3_folder  # pylint: disable=protected-access
+            )
+
+    for k, v in capabilities.options.items():
+        if hasattr(device, v):
+            device_kwargs[k] = getattr(device, v)
+
+    return BackendInfo(dname, device_name, device_lpath, device_kwargs)
+
 
 def get_qjit_device_capabilities(target_capabilities: DeviceCapabilities) -> Set[str]:
     """Calculate the set of supported quantum gates for the QJIT device from the gates
@@ -165,7 +247,7 @@ def _get_operations_to_convert_to_matrix(_capabilities: DeviceCapabilities) -> S
 
     def __init__(
         self,
-        target_config: TOMLDocument,
+        original_device_capabilities: DeviceCapabilities,
         shots=None,
         wires=None,
         backend: Optional[BackendInfo] = None,
@@ -175,23 +257,18 @@ def __init__(
         self.backend_name = backend.c_interface_name if backend else "default"
         self.backend_lib = backend.lpath if backend else ""
         self.backend_kwargs = backend.kwargs if backend else {}
-        device_name = backend.device_name if backend else "default"
 
-        program_features = ProgramFeatures(shots is not None)
-        target_device_capabilities = get_device_capabilities(
-            target_config, program_features, device_name
-        )
-        self.capabilities = get_qjit_device_capabilities(target_device_capabilities)
+        self.qjit_capabilities = get_qjit_device_capabilities(original_device_capabilities)
 
     @property
     def operations(self) -> Set[str]:
         """Get the device operations using PennyLane's syntax"""
-        return pennylane_operation_set(self.capabilities.native_ops)
+        return pennylane_operation_set(self.qjit_capabilities.native_ops)
 
     @property
     def observables(self) -> Set[str]:
         """Get the device observables"""
-        return pennylane_operation_set(self.capabilities.native_obs)
+        return pennylane_operation_set(self.qjit_capabilities.native_obs)
 
     def apply(self, operations, **kwargs):
         """
@@ -270,6 +347,7 @@ class QJITDeviceNewAPI(qml.devices.Device):
     def __init__(
         self,
         original_device,
+        original_device_capabilities: DeviceCapabilities,
         backend: Optional[BackendInfo] = None,
     ):
         self.original_device = original_device
@@ -285,29 +363,23 @@ def __init__(
         self.backend_name = backend.c_interface_name if backend else "default"
         self.backend_lib = backend.lpath if backend else ""
         self.backend_kwargs = backend.kwargs if backend else {}
-        device_name = backend.device_name if backend else "default"
 
-        target_config = device_get_toml_config(original_device)
-        program_features = ProgramFeatures(original_device.shots is not None)
-        target_device_capabilities = get_device_capabilities(
-            target_config, program_features, device_name
-        )
-        self.capabilities = get_qjit_device_capabilities(target_device_capabilities)
+        self.qjit_capabilities = get_qjit_device_capabilities(original_device_capabilities)
 
     @property
     def operations(self) -> Set[str]:
         """Get the device operations"""
-        return pennylane_operation_set(self.capabilities.native_ops)
+        return pennylane_operation_set(self.qjit_capabilities.native_ops)
 
     @property
     def observables(self) -> Set[str]:
         """Get the device observables"""
-        return pennylane_operation_set(self.capabilities.native_obs)
+        return pennylane_operation_set(self.qjit_capabilities.native_obs)
 
     @property
     def measurement_processes(self) -> Set[str]:
         """Get the device measurement processes"""
-        return self.capabilities.measurement_processes
+        return self.qjit_capabilities.measurement_processes
 
     def preprocess(
         self,
@@ -334,3 +406,101 @@ def execute(self, circuits, execution_config):
         Raises: RuntimeError
         """
         raise RuntimeError("QJIT devices cannot execute tapes.")
+
+
+def filter_out_adjoint(operations):
+    """Remove Adjoint from operations.
+
+    Args:
+        operations (List[Str]): List of strings with names of supported operations
+
+    Returns:
+        List: A list of strings with names of supported operations with Adjoint and C gates
+        removed.
+    """
+    adjoint = re.compile(r"^Adjoint\(.*\)$")
+
+    def is_not_adj(op):
+        return not re.match(adjoint, op)
+
+    operations_no_adj = filter(is_not_adj, operations)
+    return set(operations_no_adj)
+
+
+def check_no_overlap(*args, device_name):
+    """Check items in *args are mutually exclusive.
+
+    Args:
+        *args (List[Str]): List of strings.
+        device_name (str): Device name for error reporting.
+
+    Raises:
+        CompileError
+    """
+    set_of_sets = [set(arg) for arg in args]
+    union = set.union(*set_of_sets)
+    len_of_sets = [len(arg) for arg in args]
+    if sum(len_of_sets) == len(union):
+        return
+
+    overlaps = set()
+    for s in set_of_sets:
+        overlaps.update(s - union)
+        union = union - s
+
+    msg = f"Device '{device_name}' has overlapping gates: {overlaps}"
+    raise CompileError(msg)
+
+
+def validate_device_capabilities(
+    device: qml.QubitDevice, device_capabilities: DeviceCapabilities
+) -> None:
+    """Validate configuration document against the device attributes.
+    Raise CompileError in case of mismatch:
+    * If device is not qjit-compatible.
+    * If configuration file does not exists.
+    * If decomposable, matrix, and native gates have some overlap.
+    * If decomposable, matrix, and native gates do not match gates in ``device.operations`` and
+      ``device.observables``.
+
+    Args:
+        device (qml.Device): An instance of a quantum device.
+        config (TOMLDocument): A TOML document representation.
+
+    Raises: CompileError
+    """
+
+    if not device_capabilities.qjit_compatible_flag:
+        raise CompileError(
+            f"Attempting to compile program for incompatible device '{device.name}': "
+            f"Config is not marked as qjit-compatible"
+        )
+
+    device_name = device.short_name if isinstance(device, qml.Device) else device.name
+
+    native = pennylane_operation_set(device_capabilities.native_ops)
+    decomposable = pennylane_operation_set(device_capabilities.to_decomp_ops)
+    matrix = pennylane_operation_set(device_capabilities.to_matrix_ops)
+
+    check_no_overlap(native, decomposable, matrix, device_name=device_name)
+
+    if hasattr(device, "operations") and hasattr(device, "observables"):
+        # For gates, we require strict match
+        device_gates = filter_out_adjoint(set(device.operations))
+        spec_gates = filter_out_adjoint(set.union(native, matrix, decomposable))
+        if device_gates != spec_gates:
+            raise CompileError(
+                "Gates in qml.device.operations and specification file do not match.\n"
+                f"Gates that present only in the device: {device_gates - spec_gates}\n"
+                f"Gates that present only in spec: {spec_gates - device_gates}\n"
+            )
+
+        # For observables, we do not have `non-native` section in the config, so we check that
+        # device data supercedes the specification.
+        device_observables = set(device.observables)
+        spec_observables = pennylane_operation_set(device_capabilities.native_obs)
+        if (spec_observables - device_observables) != set():
+            raise CompileError(
+                "Observables in qml.device.observables and specification file do not match.\n"
+                f"Observables that present only in spec: {spec_observables - device_observables}\n"
+            )