[scraper/processscraper] Fix TestScrapeMetrics_MuteErrorFlags failures on windows and darwin (open-telemetry#28864)

**Description:** 

There were some issues related to how `mock.On` works. With default mock
and addition `On` which is already present it appends to a list and
won't be called as one instance of a method is already there. So some
expectations regarding return values were not met

Metrics count for darwin is 3 because disk io is disabled
[here](https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/f509060a8d1ab5ca4b5827e0c60d1149e3059908/receiver/hostmetricsreceiver/internal/scraper/processscraper/process_scraper.go#L315)

Tested locally on mac, windows 11 and ubuntu 22

**Link to tracking Issue:** open-telemetry#28828

Author: michalpristas

receiver/hostmetricsreceiver/internal/scraper/processscraper/process_scraper_test.go

@@ -475,23 +475,58 @@ func (p *processHandleMock) RlimitUsageWithContext(ctx context.Context, b bool)
 	return args.Get(0).([]process.RlimitStat), args.Error(1)
 }
 
-func newDefaultHandleMock() *processHandleMock {
-	handleMock := &processHandleMock{}
-	handleMock.On("UsernameWithContext", mock.Anything).Return("username", nil)
-	handleMock.On("CmdlineWithContext", mock.Anything).Return("cmdline", nil)
-	handleMock.On("CmdlineSliceWithContext", mock.Anything).Return([]string{"cmdline"}, nil)
-	handleMock.On("TimesWithContext", mock.Anything).Return(&cpu.TimesStat{}, nil)
-	handleMock.On("PercentWithContext", mock.Anything, mock.Anything).Return(float64(0), nil)
-	handleMock.On("MemoryInfoWithContext", mock.Anything).Return(&process.MemoryInfoStat{}, nil)
-	handleMock.On("MemoryPercentWithContext", mock.Anything).Return(float32(0), nil)
-	handleMock.On("IOCountersWithContext", mock.Anything).Return(&process.IOCountersStat{}, nil)
-	handleMock.On("PpidWithContext", mock.Anything).Return(int32(2), nil)
-	handleMock.On("NumThreadsWithContext", mock.Anything).Return(int32(0), nil)
-	handleMock.On("PageFaultsWithContext", mock.Anything).Return(&process.PageFaultsStat{}, nil)
-	handleMock.On("NumCtxSwitchesWithContext", mock.Anything).Return(&process.NumCtxSwitchesStat{}, nil)
-	handleMock.On("NumFDsWithContext", mock.Anything).Return(int32(0), nil)
-	handleMock.On("RlimitUsageWithContext", mock.Anything, mock.Anything).Return([]process.RlimitStat{}, nil)
-	return handleMock
+func initDefaultsHandleMock(t mock.TestingT, handleMock *processHandleMock) {
+	if !handleMock.IsMethodCallable(t, "UsernameWithContext", mock.Anything) {
+		handleMock.On("UsernameWithContext", mock.Anything).Return("username", nil)
+	}
+	if !handleMock.IsMethodCallable(t, "NameWithContext", mock.Anything) {
+		handleMock.On("NameWithContext", mock.Anything).Return("processname", nil)
+	}
+	if !handleMock.IsMethodCallable(t, "CmdlineWithContext", mock.Anything) {
+		handleMock.On("CmdlineWithContext", mock.Anything).Return("cmdline", nil)
+	}
+	if !handleMock.IsMethodCallable(t, "CmdlineSliceWithContext", mock.Anything) {
+		handleMock.On("CmdlineSliceWithContext", mock.Anything).Return([]string{"cmdline"}, nil)
+	}
+	if !handleMock.IsMethodCallable(t, "TimesWithContext", mock.Anything) {
+		handleMock.On("TimesWithContext", mock.Anything).Return(&cpu.TimesStat{}, nil)
+	}
+	if !handleMock.IsMethodCallable(t, "PercentWithContext", mock.Anything, mock.Anything) {
+		handleMock.On("PercentWithContext", mock.Anything, mock.Anything).Return(float64(0), nil)
+	}
+	if !handleMock.IsMethodCallable(t, "MemoryInfoWithContext", mock.Anything) {
+		handleMock.On("MemoryInfoWithContext", mock.Anything).Return(&process.MemoryInfoStat{}, nil)
+	}
+	if !handleMock.IsMethodCallable(t, "MemoryPercentWithContext", mock.Anything) {
+		handleMock.On("MemoryPercentWithContext", mock.Anything).Return(float32(0), nil)
+	}
+	if !handleMock.IsMethodCallable(t, "IOCountersWithContext", mock.Anything) {
+		handleMock.On("IOCountersWithContext", mock.Anything).Return(&process.IOCountersStat{}, nil)
+	}
+	if !handleMock.IsMethodCallable(t, "PpidWithContext", mock.Anything) {
+		handleMock.On("PpidWithContext", mock.Anything).Return(int32(2), nil)
+	}
+	if !handleMock.IsMethodCallable(t, "NumThreadsWithContext", mock.Anything) {
+		handleMock.On("NumThreadsWithContext", mock.Anything).Return(int32(0), nil)
+	}
+	if !handleMock.IsMethodCallable(t, "PageFaultsWithContext", mock.Anything) {
+		handleMock.On("PageFaultsWithContext", mock.Anything).Return(&process.PageFaultsStat{}, nil)
+	}
+	if !handleMock.IsMethodCallable(t, "NumCtxSwitchesWithContext", mock.Anything) {
+		handleMock.On("NumCtxSwitchesWithContext", mock.Anything).Return(&process.NumCtxSwitchesStat{}, nil)
+	}
+	if !handleMock.IsMethodCallable(t, "NumFDsWithContext", mock.Anything) {
+		handleMock.On("NumFDsWithContext", mock.Anything).Return(int32(0), nil)
+	}
+	if !handleMock.IsMethodCallable(t, "RlimitUsageWithContext", mock.Anything, mock.Anything) {
+		handleMock.On("RlimitUsageWithContext", mock.Anything, mock.Anything).Return([]process.RlimitStat{}, nil)
+	}
+	if !handleMock.IsMethodCallable(t, "CreateTimeWithContext", mock.Anything) {
+		handleMock.On("CreateTimeWithContext", mock.Anything).Return(time.Now().UnixMilli(), nil)
+	}
+	if !handleMock.IsMethodCallable(t, "ExeWithContext", mock.Anything) {
+		handleMock.On("ExeWithContext", mock.Anything).Return("processname", nil)
+	}
 }
 
 func TestScrapeMetrics_Filtered(t *testing.T) {
@@ -598,10 +633,12 @@ func TestScrapeMetrics_Filtered(t *testing.T) {
 
 			handles := make([]*processHandleMock, 0, len(test.names))
 			for i, name := range test.names {
-				handleMock := newDefaultHandleMock()
+				handleMock := &processHandleMock{}
 				handleMock.On("NameWithContext", mock.Anything).Return(name, nil)
 				handleMock.On("ExeWithContext", mock.Anything).Return(name, nil)
 				handleMock.On("CreateTimeWithContext", mock.Anything).Return(time.Now().UnixMilli()-test.upTimeMs[i], nil)
+				initDefaultsHandleMock(t, handleMock)
+
 				handles = append(handles, handleMock)
 			}
 
@@ -1001,22 +1038,34 @@ func TestScrapeMetrics_MuteErrorFlags(t *testing.T) {
 		},
 		{
 			name:                 "Process User Error Muted",
-			skipTestCase:         runtime.GOOS != "linux",
 			muteProcessUserError: true,
 			skipProcessNameError: true,
 			muteProcessExeError:  true,
 			muteProcessNameError: true,
-			expectedCount:        4,
+			expectedCount: func() int {
+				if runtime.GOOS == "darwin" {
+					// disk.io is not collected on darwin
+					return 3
+				}
+				return 4
+			}(),
 		},
 		{
 			name:                 "Process User Error Unmuted",
-			skipTestCase:         runtime.GOOS != "linux",
 			muteProcessUserError: false,
 			skipProcessNameError: true,
 			muteProcessExeError:  true,
 			muteProcessNameError: true,
-			expectedError:        fmt.Sprintf("error reading username for process \"processname\" (pid 1): %v", processNameError),
-			expectedCount:        4,
+			expectedError: func() string {
+				return fmt.Sprintf("error reading username for process \"processname\" (pid 1): %v", processNameError)
+			}(),
+			expectedCount: func() int {
+				if runtime.GOOS == "darwin" {
+					// disk.io is not collected on darwin
+					return 3
+				}
+				return 4
+			}(),
 		},
 	}
 
@@ -1037,21 +1086,17 @@ func TestScrapeMetrics_MuteErrorFlags(t *testing.T) {
 			err = scraper.start(context.Background(), componenttest.NewNopHost())
 			require.NoError(t, err, "Failed to initialize process scraper: %v", err)
 
-			handleMock := newDefaultHandleMock()
+			handleMock := &processHandleMock{}
 			if !test.skipProcessNameError {
 				handleMock.On("NameWithContext", mock.Anything).Return("test", processNameError)
+				handleMock.On("ExeWithContext", mock.Anything).Return("test", processNameError)
+				handleMock.On("CmdlineWithContext", mock.Anything).Return("test", processNameError)
 			} else {
-				for _, c := range handleMock.ExpectedCalls {
-					if c.Method == "UsernameWithContext" {
-						c.ReturnArguments = []interface{}{"processname", processNameError}
-						break
-					}
-				}
+				handleMock.On("UsernameWithContext", mock.Anything).Return("processname", processNameError)
 				handleMock.On("NameWithContext", mock.Anything).Return("processname", nil)
 				handleMock.On("CreateTimeWithContext", mock.Anything).Return(time.Now().UnixMilli(), nil)
 			}
-			handleMock.On("ExeWithContext", mock.Anything).Return("test", processNameError)
-			handleMock.On("CmdlineWithContext", mock.Anything).Return("test", processNameError)
+			initDefaultsHandleMock(t, handleMock)
 
 			if config.MuteProcessIOError {
 				handleMock.On("IOCountersWithContext", mock.Anything).Return("test", errors.New("permission denied"))
@@ -1182,10 +1227,11 @@ func TestScrapeMetrics_CpuUtilizationWhenCpuTimesIsDisabled(t *testing.T) {
 			err = scraper.start(context.Background(), componenttest.NewNopHost())
 			require.NoError(t, err, "Failed to initialize process scraper: %v", err)
 
-			handleMock := newDefaultHandleMock()
+			handleMock := &processHandleMock{}
 			handleMock.On("NameWithContext", mock.Anything).Return("test", nil)
 			handleMock.On("ExeWithContext", mock.Anything).Return("test", nil)
 			handleMock.On("CreateTimeWithContext", mock.Anything).Return(time.Now().UnixMilli(), nil)
+			initDefaultsHandleMock(t, handleMock)
 
 			scraper.getProcessHandles = func(context.Context) (processHandles, error) {
 				return &processHandlesMock{handles: []*processHandleMock{handleMock}}, nil