pull-3135-pipelinerun.json

 kubectl get pr -o json
{
    "apiVersion": "v1",
    "items": [
        {
            "apiVersion": "tekton.dev/v1beta1",
            "kind": "PipelineRun",
            "metadata": {
                "annotations": {
                    "kubectl.kubernetes.io/last-applied-configuration": "{\"apiVersion\":\"tekton.dev/v1beta1\",\"kind\":\"PipelineRun\",\"metadata\":{\"annotations\":{},\"name\":\"pipelinerun-to-skip-task\",\"namespace\":\"default\"},\"spec\":{\"params\":[{\"name\":\"param\",\"value\":\"spec\"}],\"pipelineSpec\":{\"params\":[{\"default\":\"pipelineSpec\",\"name\":\"param\"}],\"tasks\":[{\"name\":\"skip-this-task\",\"taskSpec\":{\"steps\":[{\"image\":\"ubuntu\",\"name\":\"echo\",\"script\":\"#!/usr/bin/env bash\\necho \\\"Good Morning!\\\"\\n\"}]},\"when\":[{\"input\":\"$(params.param)\",\"operator\":\"in\",\"values\":[\"foo\"]}]},{\"name\":\"execute-this-task\",\"runAfter\":[\"skip-this-task\"],\"taskSpec\":{\"steps\":[{\"image\":\"ubuntu\",\"name\":\"echo\",\"script\":\"#!/usr/bin/env bash\\necho \\\"Good Morning!\\\"\\n\"}]},\"when\":[{\"input\":\"bar\",\"operator\":\"in\",\"values\":[\"bar\"]}]}]}}}\n"
                },
                "creationTimestamp": "2020-08-27T05:47:58Z",
                "generation": 1,
                "labels": {
                    "tekton.dev/pipeline": "pipelinerun-to-skip-task"
                },
                "name": "pipelinerun-to-skip-task",
                "namespace": "default",
                "resourceVersion": "2063663",
                "selfLink": "/apis/tekton.dev/v1beta1/namespaces/default/pipelineruns/pipelinerun-to-skip-task",
                "uid": "dde3a2f8-2cd9-4463-9122-962a73d9aa49"
            },
            "spec": {
                "params": [
                    {
                        "name": "param",
                        "value": "spec"
                    }
                ],
                "pipelineSpec": {
                    "params": [
                        {
                            "default": "pipelineSpec",
                            "name": "param",
                            "type": "string"
                        }
                    ],
                    "tasks": [
                        {
                            "name": "skip-this-task",
                            "taskSpec": {
                                "metadata": {},
                                "steps": [
                                    {
                                        "image": "ubuntu",
                                        "name": "echo",
                                        "resources": {},
                                        "script": "#!/usr/bin/env bash\necho \"Good Morning!\"\n"
                                    }
                                ]
                            },
                            "when": [
                                {
                                    "input": "$(params.param)",
                                    "operator": "in",
                                    "values": [
                                        "foo"
                                    ]
                                }
                            ]
                        },
                        {
                            "name": "execute-this-task",
                            "runAfter": [
                                "skip-this-task"
                            ],
                            "taskSpec": {
                                "metadata": {},
                                "steps": [
                                    {
                                        "image": "ubuntu",
                                        "name": "echo",
                                        "resources": {},
                                        "script": "#!/usr/bin/env bash\necho \"Good Morning!\"\n"
                                    }
                                ]
                            },
                            "when": [
                                {
                                    "input": "bar",
                                    "operator": "in",
                                    "values": [
                                        "bar"
                                    ]
                                }
                            ]
                        }
                    ]
                },
                "timeout": "1h0m0s"
            },
            "status": {
                "completionTime": "2020-08-27T05:47:58Z",
                "conditions": [
                    {
                        "lastTransitionTime": "2020-08-27T05:47:58Z",
                        "message": "Tasks Completed: 0 (Failed: 0, Cancelled 0), Skipped: 2",
                        "reason": "Completed",
                        "status": "True",
                        "type": "Succeeded"
                    }
                ],
                "pipelineSpec": {
                    "params": [
                        {
                            "default": "pipelineSpec",
                            "name": "param",
                            "type": "string"
                        }
                    ],
                    "tasks": [
                        {
                            "name": "skip-this-task",
                            "taskSpec": {
                                "metadata": {},
                                "steps": [
                                    {
                                        "image": "ubuntu",
                                        "name": "echo",
                                        "resources": {},
                                        "script": "#!/usr/bin/env bash\necho \"Good Morning!\"\n"
                                    }
                                ]
                            },
                            "when": [
                                {
                                    "input": "$(params.param)",
                                    "operator": "in",
                                    "values": [
                                        "foo"
                                    ]
                                }
                            ]
                        },
                        {
                            "name": "execute-this-task",
                            "runAfter": [
                                "skip-this-task"
                            ],
                            "taskSpec": {
                                "metadata": {},
                                "steps": [
                                    {
                                        "image": "ubuntu",
                                        "name": "echo",
                                        "resources": {},
                                        "script": "#!/usr/bin/env bash\necho \"Good Morning!\"\n"
                                    }
                                ]
                            },
                            "when": [
                                {
                                    "input": "bar",
                                    "operator": "in",
                                    "values": [
                                        "bar"
                                    ]
                                }
                            ]
                        }
                    ]
                },
                "startTime": "2020-08-27T05:47:58Z",
                "taskRuns": {
                    "pipelinerun-to-skip-task-execute-this-task-wvh5s": {
                        "pipelineTaskName": "execute-this-task",
                        "status": {
                            "podName": ""
                        },
                        "whenExpressionsStatus": {
                            "evaluationResults": [
                                {
                                    "expression": {
                                        "input": "bar",
                                        "operator": "in",
                                        "values": [
                                            "bar"
                                        ]
                                    },
                                    "result": true
                                }
                            ],
                            "execute": true
                        }
                    },
                    "pipelinerun-to-skip-task-skip-this-task-bmrxs": {
                        "pipelineTaskName": "skip-this-task",
                        "status": {
                            "conditions": [
                                {
                                    "lastTransitionTime": "2020-08-27T05:47:58Z",
                                    "message": "When Expressions for Task pipelinerun-to-skip-task-skip-this-task-bmrxs in PipelineRun pipelinerun-to-skip-task evaluated to False",
                                    "reason": "WhenExpressionsEvaluatedToFalse",
                                    "status": "False",
                                    "type": "Succeeded"
                                }
                            ],
                            "podName": ""
                        },
                        "whenExpressionsStatus": {
                            "evaluationResults": [
                                {
                                    "expression": {
                                        "input": "spec",
                                        "operator": "in",
                                        "values": [
                                            "foo"
                                        ]
                                    }
                                }
                            ]
                        }
                    }
                }
            }
        }
    ],
    "kind": "List",
    "metadata": {
        "resourceVersion": "",
        "selfLink": ""
    }
}

Sample PipelineRun:

apiVersion: tekton.dev/v1beta1
kind: PipelineRun
metadata:
  name: pipelinerun-to-skip-task
spec:
  params:
    - name: param
      value: "spec"
  pipelineSpec:
    params:
      - name: param
        default: "pipelineSpec"
    tasks:
      - name: skip-this-task
        when:
          - input: $(params.param)
            operator: in
            values: ["foo"]
        taskSpec:
          steps:
            - name: echo
              image: ubuntu
              script: |
                #!/usr/bin/env bash
                echo "Good Morning!"
      - name: execute-this-task
        runAfter: ["skip-this-task"]
        when:
          - input: "bar"
            operator: in
            values: ["bar"]
        taskSpec:
          steps:
            - name: echo
              image: ubuntu
              script: |
                #!/usr/bin/env bash
                echo "Good Morning!"
---