New test for factor

[lohani2280]

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Refers #590

Changes

Please list the proposed changes in this pull request.

• Separated the tests for Factor, TabularCPD and JointProbabilityDistribution classes
• test_Factor: Added test for copy method
• test_Factor: Added test for sum method
• test_Factor: Added test for repr method of DiscreteFactor class
• Added test for get_evidence method of TabularCPD class
• Added test for to_factor method of TabularCPD class
• test_JointProbabilityDistribution: Added test for copy method of JointProbabilityDistribution class
• test_JointProbabilityDistribution: Added test for to_factor method of JointProbabilityDistribution class

💔Thank you!

[lohani2280]

Ping @khalibartan @ankurankan

[ankurankan]

@lohani2280 Sorry for replying so late. This will have to wait for a while till I push the refactor of the factor dir.

[lohani2280]

@ankurankan No issues. I have added some additional test which were not present earlier. If you are free sometime,then please have a look and suggest necessary changes.