fix reading yarn version

continuation of #740 with tests added

Author: arjun024

src/nodejs/supply/supply.go

@@ -789,7 +789,7 @@ func (s *Supplier) InstallYarn() error {
 	}
 
 	buffer := new(bytes.Buffer)
-	if err := s.Command.Execute(s.Stager.BuildDir(), buffer, buffer, "yarn", "--version"); err != nil {
+	if err := s.Command.Execute(s.Stager.BuildDir(), buffer, buffer, "yarn", "--version", "--loglevel", "notice"); err != nil {
 		return err
 	}
 

src/nodejs/supply/supply_test.go

@@ -596,7 +596,7 @@ var _ = Describe("Supply", func() {
 			BeforeEach(func() {
 				mockInstaller.EXPECT().InstallOnlyVersion("yarn", yarnInstallDir).Do(installOnlyYarn).Return(nil)
 
-				mockCommand.EXPECT().Execute(buildDir, gomock.Any(), gomock.Any(), "yarn", "--version").Do(func(_ string, buffer io.Writer, _ io.Writer, _ string, _ string) {
+				mockCommand.EXPECT().Execute(buildDir, gomock.Any(), gomock.Any(), "yarn", "--version", "--loglevel", "notice").Do(func(_ string, buffer io.Writer, _ io.Writer, _ string, _ ...string) {
 					buffer.Write([]byte("0.32.5\n"))
 				}).Return(nil)
 			})
@@ -630,7 +630,7 @@ var _ = Describe("Supply", func() {
 				mockManifest.EXPECT().AllDependencyVersions("yarn").Return(versions)
 				mockInstaller.EXPECT().InstallOnlyVersion("yarn", yarnInstallDir).Do(installOnlyYarn).Return(nil)
 
-				mockCommand.EXPECT().Execute(buildDir, gomock.Any(), gomock.Any(), "yarn", "--version").Do(func(_ string, buffer io.Writer, _ io.Writer, _ string, _ string) {
+				mockCommand.EXPECT().Execute(buildDir, gomock.Any(), gomock.Any(), "yarn", "--version", "--loglevel", "notice").Do(func(_ string, buffer io.Writer, _ io.Writer, _ string, _ ...string) {
 					buffer.Write([]byte("0.32.5\n"))
 				}).Return(nil)
 			})
@@ -661,7 +661,7 @@ var _ = Describe("Supply", func() {
 
 	Describe("InstallNPM", func() {
 		BeforeEach(func() {
-			mockCommand.EXPECT().Execute(buildDir, gomock.Any(), gomock.Any(), "npm", "--version").Do(func(_ string, buffer io.Writer, _ io.Writer, _ string, _ string) {
+			mockCommand.EXPECT().Execute(buildDir, gomock.Any(), gomock.Any(), "npm", "--version", "--loglevel", "notice").Do(func(_ string, buffer io.Writer, _ io.Writer, _ string, _ ...string) {
 				buffer.Write([]byte("1.2.3\n"))
 			}).Return(nil)
 		})