[INFO] `Scanning for projects`...
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[INFO] `Building MVNDEMO 0.0.1-SNAPSHOT`
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[INFO] `BUILD FAILURE`
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[INFO] `Total time: 0.099 s
[INFO] Finished at: 2019-04-25T12:29:22+05:30
[INFO] Final Memory: 5M/123M`
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[ERROR] Unknown lifecycle phase "testcases". You must specify a valid lifecycle phase or a goal in the format <plugin-prefix>:<goal> or <plugin-group-id>:<plugin-artifact-id>[:<plugin-version>]:<goal>. Available lifecycle phases are: validate, initialize, generate-sources, process-sources, generate-resources, process-resources, compile, process-classes, generate-test-sources, process-test-sources, generate-test-resources, process-test-resources, test-compile, process-test-classes, test, prepare-package, package, pre-integration-test, integration-test, post-integration-test, verify, install, deploy, pre-clean, clean, post-clean, pre-site, site, post-site, site-deploy. -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1]
你称之为mvn testcases，这不是一个有效的Maven阶段。
如果你想建立，使用mvn clean install。