fix(cli): Report error if unwanted positional arguments are received (#…

…1100)

This applies to check-coverage, instrument, merge and report.  Passing
additional arguments will now cause the help script to be displayed and
an error exit code.

Unknown flags `nyc report --unknown=1` are still not reported.
Reporting unknown flags would require additional work as
`yargs.strict()` causes unknown items from configuration to be reported,
including flags that are defined for the global command but not a
sub-command.

Fixes #401

lib/commands/check-coverage.js

@@ -7,6 +7,7 @@ exports.describe = 'check whether coverage is within thresholds provided'
 
 exports.builder = function (yargs) {
   yargs
+    .demandCommand(0, 0)
     .option('exclude', {
       alias: 'x',
       default: testExclude.defaultExclude,

lib/commands/instrument.js

@@ -9,6 +9,15 @@ exports.describe = 'instruments a file or a directory tree and writes the instru
 
 exports.builder = function (yargs) {
   return yargs
+    .demandCommand(0, 0)
+    .positional('input', {
+      describe: 'file or directory to instrument',
+      type: 'text'
+    })
+    .positional('output', {
+      describe: 'directory to output instrumented files',
+      type: 'text'
+    })
     .option('require', {
       alias: 'i',
       default: [],

lib/commands/merge.js

@@ -11,6 +11,7 @@ exports.describe = 'merge istanbul format coverage output in a given folder'
 
 exports.builder = function (yargs) {
   return yargs
+    .demandCommand(0, 0)
     .positional('input-directory', {
       describe: 'directory containing multiple istanbul coverage files',
       type: 'text',

lib/commands/report.js

@@ -7,6 +7,7 @@ exports.describe = 'run coverage report for .nyc_output'
 
 exports.builder = function (yargs) {
   return yargs
+    .demandCommand(0, 0)
     .option('reporter', {
       alias: 'r',
       describe: 'coverage reporter(s) to use',

tap-snapshots/test-nyc-integration.js-TAP.test.js

@@ -20,25 +20,6 @@ All files                |    33.33 |        0 |      100 |    33.33 |
 
 `
 
-exports[`test/nyc-integration.js TAP --check-coverage fails when check-coverage command is used rather than flag > stderr 1`] = `
-ERROR: Coverage for lines (50%) does not meet global threshold (51%)
-
-`
-
-exports[`test/nyc-integration.js TAP --check-coverage fails when check-coverage command is used rather than flag > stdout 1`] = `
------------------|----------|----------|----------|----------|-------------------|
-File             |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
------------------|----------|----------|----------|----------|-------------------|
-All files        |       50 |       50 |      100 |       50 |                   |
- half-covered.js |       50 |       50 |      100 |       50 |             6,7,8 |
------------------|----------|----------|----------|----------|-------------------|
-
-`
-
-exports[`test/nyc-integration.js TAP --check-coverage fails when check-coverage command is used rather than flag > stdout 2`] = `
-
-`
-
 exports[`test/nyc-integration.js TAP --check-coverage fails when the expected coverage is below a threshold > stderr 1`] = `
 ERROR: Coverage for lines (50%) does not meet global threshold (51%)
 
@@ -310,6 +291,25 @@ end_of_record
 
 `
 
+exports[`test/nyc-integration.js TAP check-coverage command is equivalent to the flag > stderr 1`] = `
+ERROR: Coverage for lines (50%) does not meet global threshold (51%)
+
+`
+
+exports[`test/nyc-integration.js TAP check-coverage command is equivalent to the flag > stdout 1`] = `
+-----------------|----------|----------|----------|----------|-------------------|
+File             |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
+-----------------|----------|----------|----------|----------|-------------------|
+All files        |       50 |       50 |      100 |       50 |                   |
+ half-covered.js |       50 |       50 |      100 |       50 |             6,7,8 |
+-----------------|----------|----------|----------|----------|-------------------|
+
+`
+
+exports[`test/nyc-integration.js TAP check-coverage command is equivalent to the flag > stdout 2`] = `
+
+`
+
 exports[`test/nyc-integration.js TAP does not interpret args intended for instrumented bin > undefined 1`] = `
 [ '--help', '--version' ]
 `

test/nyc-integration.js

@@ -45,11 +45,11 @@ t.test('--check-coverage fails when the expected coverage is below a threshold',
 }))
 
 // https://github.com/istanbuljs/nyc/issues/384
-t.test('--check-coverage fails when check-coverage command is used rather than flag', t => {
+t.test('check-coverage command is equivalent to the flag', t => {
   return testSuccess(t, {
     args: [process.execPath, './half-covered.js']
   }).then(() => testFailure(t, {
-    args: ['check-coverage', '--lines', '51', process.execPath, './half-covered.js']
+    args: ['check-coverage', '--lines', '51']
   }))
 })