test(coverage): improve coverage config

[leonardobazico]

Description

I've noticed that the test coverage is collecting data from dist and src.

Motivation and Context

Improve the collaboration experience and maintenance.
It will also enable a better yarn test --watch usability, cause the test-kit will look for the source code.

Previous coverage result

---------------------------|---------|----------|---------|---------|------------------------------------------
File                       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s                        
---------------------------|---------|----------|---------|---------|------------------------------------------
All files                  |   84.66 |    72.65 |   82.07 |   84.95 |                                          
 dist                      |    90.8 |    74.63 |   92.86 |   90.94 |                                          
  _handlers.js             |   91.18 |       68 |     100 |   91.18 | 48,54,65                                 
  config-factory.js        |   96.88 |    82.61 |     100 |   96.88 | 38                                       
  context-matcher.js       |   94.44 |       90 |     100 |   94.44 | 25,32                                    
  errors.js                |     100 |      100 |     100 |     100 |                                          
  http-proxy-middleware.js |    96.2 |    83.67 |     100 |    96.2 | 101-102,125                              
  index.js                 |   84.21 |    68.75 |      80 |   85.71 | 6-7                                      
  logger.js                |   70.69 |       50 |   81.25 |   70.18 | 38,42,51-52,73,81,118-133                
  path-rewriter.js         |   97.06 |    81.25 |     100 |   97.06 | 51                                       
  router.js                |     100 |       90 |     100 |     100 | 13                                       
 dist/handlers             |   43.21 |    52.63 |   33.33 |   42.25 |                                          
  fix-request-body.js      |   92.86 |       90 |     100 |   92.86 | 10                                       
  index.js                 |   78.57 |    68.75 |      75 |   77.78 | 6-7                                      
  public.js                |    87.5 |      100 |      50 |     100 |                                          
  response-interceptor.js  |    8.89 |        0 |       0 |    9.52 | 13-31,41-84                              
 src                       |   89.53 |    77.84 |   90.38 |   89.49 |                                          
  _handlers.ts             |   96.88 |       96 |      75 |   96.88 | 87                                       
  config-factory.ts        |   93.33 |    82.61 |     100 |   93.33 | 84,88                                    
  context-matcher.ts       |     100 |      100 |     100 |     100 |                                          
  errors.ts                |     100 |      100 |     100 |     100 |                                          
  http-proxy-middleware.ts |   63.64 |    32.65 |   63.64 |   63.64 | ...96-99,141-147,164-168,176-181,187-194 
  index.ts                 |     100 |      100 |     100 |     100 |                                          
  logger.ts                |     100 |       95 |     100 |     100 | 72-78                                    
  path-rewriter.ts         |     100 |    93.75 |     100 |     100 | 57                                       
  router.ts                |     100 |      100 |     100 |     100 |                                          
 src/handlers              |      80 |    45.45 |   71.43 |   78.18 |                                          
  fix-request-body.ts      |   16.67 |        0 |       0 |   16.67 | 9-25                                     
  index.ts                 |     100 |      100 |     100 |     100 |                                          
  public.ts                |     100 |      100 |      50 |     100 |                                          
  response-interceptor.ts  |   95.35 |    83.33 |      90 |      95 | 48,109                                   
 test/e2e                  |     100 |      100 |      80 |     100 |                                          
  test-kit.ts              |     100 |      100 |      80 |     100 |                                          
---------------------------|---------|----------|---------|---------|------------------------------------------

Coverage result after config changes

---------------------------|---------|----------|---------|---------|-------------------
File                       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
---------------------------|---------|----------|---------|---------|-------------------
All files                  |   98.31 |    91.79 |   98.48 |   98.29 |                   
 src                       |   98.99 |    92.43 |     100 |   98.98 |                   
  _handlers.ts             |     100 |       96 |     100 |     100 | 70                
  config-factory.ts        |     100 |     91.3 |     100 |     100 | 29,79             
  context-matcher.ts       |     100 |      100 |     100 |     100 |                   
  errors.ts                |     100 |      100 |     100 |     100 |                   
  http-proxy-middleware.ts |    96.1 |    83.67 |     100 |    96.1 | 141-147,181       
  index.ts                 |     100 |      100 |     100 |     100 |                   
  logger.ts                |     100 |       95 |     100 |     100 | 72-78             
  path-rewriter.ts         |     100 |    93.75 |     100 |     100 | 57                
  router.ts                |     100 |      100 |     100 |     100 |                   
 src/handlers              |      95 |    86.36 |   92.86 |   94.55 |                   
  fix-request-body.ts      |   91.67 |       90 |     100 |   91.67 | 10                
  index.ts                 |     100 |      100 |     100 |     100 |                   
  public.ts                |     100 |      100 |     100 |     100 |                   
  response-interceptor.ts  |   95.35 |    83.33 |      90 |      95 | 48,109            
---------------------------|---------|----------|---------|---------|-------------------

How has this been tested?

Not need

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[coveralls]

Coverage increased (+13.3%) to 98.286% when pulling 3cda05a on leonardobazico:coverage into c935888 on chimurai:master.

[chimurai]

Thanks, this was on my TODO list.

This reason for testing dist was due this little annoying TypeScript behaviour:

http-proxy-middleware/src/http-proxy-middleware.ts

Lines 45 to 46 in c935888

	// https://github.com/Microsoft/TypeScript/wiki/'this'-in-TypeScript#red-flags-for-this
	public middleware: RequestHandler = async (

Testing it purely in typescript src didn't caught this issue.

Think it makes sense to create a separate dist test, so it doesn't affect the developer experience.