[SalesForce] Field not writable: ContentVersion.FileType

As per docs :

http://www.salesforce.com/us/developer/docs/api/Content/sforce_api_objects_contentversion.htm The reason why the document was changed. This field can only be set when inserting a new version (revising) a document.

Refer this for revising an existing document if you did not get a chance to look at this : http://www.salesforce.com/docs/developer/cookbook/Content/revise_document.htm

Hope this helps.

        // Create a content version object  
        ContentVersion contentVersion = new ContentVersion();

        // Set the mandatory field pathOnClient  
        contentVersion.setPathOnClient(
                testUploadFile.getAbsolutePath());

        // Set the binary file data  
        contentVersion.setVersionData(readData);

        // Set the document ID of the document you wish to revise  
        contentVersion.setContentDocumentId(new ID("069x00000000C0j"));

        // Set the reason for change field on revision  
        contentVersion.setReasonForChange("Added total cost of"
                + "ownership graph");

        // You can add multiple versions if required by adding  
        // them to the array  
        SObject[] array = new SObject[] { contentVersion };
        SaveResult[] saveResultArray = binding.create(array);
        for (SaveResult sr : saveResultArray) {
            if (sr.isSuccess()) {
                System.out.println("created version with id:"
                        +  sr.getId());
            }
            else {
                System.out.println("Failed to create entity");
                for (Error error : sr.getErrors()) {
                    System.out.println(error.getMessage());
                }
            }
        }        

OpportunityPartner records are read-only and are created automatically by Salesforce

when a Partner object is created for a partner relationship between an account and an opportunity.

Creating an Account-Opportunity Partner Relationship

When you create a partner relationship between an account and an opportunity (when you create a Partner object and specify the OpportunityId field), the API automatically creates an OpportunityPartner with the corresponding values:

• The value of the Partner field AccountToId maps to the value of the OpportunityPartner field AccountToId.
• The values of the OpportunityId, Role, and IsPrimary fields in both objects are the same.
• If you set the IsPrimary value to 1 (true) upon insert of a new OpportunityPartner, any other existing primary partners for that opportunity will automatically have the IsPrimary value set to 0 (false).

Also, they share the 00I keyprefix with Partner. As such, I tend to think of them as a specialised view over Partner.

So you shouldn't need to explicitly insert the record during a test case. The Partner object that you insert will have accountToId to an Account and opportunityId to an Opportunity on a different Account.