Various .vscode files used to work with: https://github.com/elastic/ml-cpp

c_cpp_properties.json

{
    "configurations": [
        {
            "name": "Mac",
            "includePath": [
                "${workspaceFolder}/**",
                "/usr/local/include/boost-1_65_1/",
                "/usr/local/include",
                "/usr/include"
            ]
            "macFrameworkPath": [
                "/System/Library/Frameworks",
                "/Library/Frameworks"
            ],
            "compilerPath": "/usr/bin/clang",
            "cStandard": "c11",
            "cppStandard": "c++14",
            "intelliSenseMode": "clang-x64",
            "browse": {
                "path": [
                    "${workspaceFolder}"
                ],
                "limitSymbolsToIncludedHeaders": true,
                "databaseFilename": ""
            }
        }
    ],
    "version": 4
}

launch.json

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "api unittest Launch",
            "type": "cppdbg",
            "request": "launch",
            "program": "${workspaceFolder}/lib/api/unittest/ml_test",
            "args": [],
            "cwd": "${workspaceFolder}/lib/api/unittest",
            "environment": [
                {"name": "ML_DEBUG", "value": "true"}
            ],
            "externalConsole": true,
            "MIMode": "lldb",
            "preLaunchTask": "build api tests"
        }
    ]
}

tasks.json

{
    "version": "2.0.0",
    "tasks": [
        {
            "label": "clean api tests",
            "type": "shell",
            "command": "make clean",
            "group": "build",
            "options": {
                "cwd": "${workspaceFolder}/lib/api/unittest",
            },
        },
        {
            "label": "clean all",
            "type": "shell",
            "command": "make clean",
            "group": "build",
            "options": {
                "cwd": "${workspaceFolder}",
            },
        },
        {
            "label": "build all with debug",
            "type": "shell",
            "command": "make -j7",
            "group": {
                "kind": "build",
                "isDefault": true
            },
            "options": {
                "cwd": "${workspaceFolder}",
                "env": {
                    "ML_DEBUG": "true"
                }
            }
        },
        {
            "label": "build api tests",
            "type": "shell",
            "command": "make -j7",
            "group": {
                "kind": "build",
                "isDefault": true
            },
            "options": {
                "cwd": "${workspaceFolder}/lib/api/unittest",
                "env": {
                    "ML_DEBUG": "true"
                }
            },
            "dependsOn": ["build all with debug"]
        }
    ]
}

https://gist.github.com/benwtrent/1e4d1c5943ac1df239d4dea9ce9f7df2#file-launch-json-L9

Put the specific test name in there like, "args": ["CStringStoreTest::testAttributeStringPruning"].

Periodically, the debugger fails to attach the ml_test executable. Usually simply running again works out ok.