You are presented with multiple paper abstracts, alongside the associated literature review and chapter titles. Given the provided information, you are going to do a literature review. Please generate a coherent literature review that synthesizes the content, draws connections between different works, highlights major findings, and identifies any gaps in the existing research.

Literature Review Title: Testing L2 Talk: A Review of Empirical Studies on Second-Language Oral Proficiency Testing 
Chapter Title:  The OPI as a Unique Type of Social Event 
1. Abstract of Cited Paper (BIB001):  This is a study of the assessment of the speaking skills of adult learners of English for speakers of other languages (ESOL). It is prompted by a concern that participants can have differing expectations of what nature of speech event a speaking test actually is. This concern was identified during the administration and analysis of assessments carried out as part of a study into adult ESOL pedagogy in the UK. The paper employs the notions of knowledge schema and frame in discourse to draw together areas of interest in testing: whether the speaking assessment should be viewed as an interview or as a conversation; divergent interpretations of the test event by learners; and variation in interlocutor behaviour. Implications for testing the speaking skills of adult ESOL learners are discussed; these are pertinent at a time of large-scale high-stakes testing of learners who are migrants to English speaking countries. 
2. Abstract of Cited Paper (BIB002):  This study is based on the analysis of transcripts of 137 audio-recorded tests using a Conversation Analysis (CA) methodology. The institutional aim of standardisation in relation to assessment is shown to be the key principle underlying the organisation of the interaction. Overall, the vast majority of examiners conform to the instructions; in cases where they do not do so, they often give an advantage to some candidates. The overall organisation of the interaction is highly constrained, although there are some differences in the different parts of the test. The organisation of repair has a number of distinctive characteristics in that it is conducted according to strictly specified rules, in which the examiners have been briefed and trained. Speaking test interaction is an institutional variety of interaction with three sub-varieties. It is very different to ordinary conversation, has some similarities with some sub-varieties of L2 classroom interaction and some similarities with interaction in universities. A number of recommendations are made in relation to examiner training, instructions and test design. 
3. Abstract of Cited Paper (BIB003):  This study investigates the extent to which oral proficiency interviews (OPIs) may be described as interactional varieties, which may then be compared with interaction in university and L2 classroom settings. The three varieties are related in terms of preparing students for a next stage in an educational process. L2 classroom interaction may prepare students for examinations such as OPIs, which provide access to universities, which in turn may prepare students for the world of work.1 Therefore, it is legitimate to examine the varieties in terms of whether the interactional experiences of students align or not in the different settings. OPIs in general are intended to assess the language proficiency of non-native speakers and to predict their ability to communicate in future encounters.

Literature Review:
In the first topical theme identified, efforts to define the type of social event that OPIs constitute are made. Given the aim of eliciting candidates' L2 conversational competence, many studies focus on defining the type of social interaction that such interviews may represent, that is, whether OPIs resemble ordinary conversations and whether this interactional type of event is suitable for assessing L2 communicative skills BIB002 ) (cf. also older extensive reviews in   BIB001 . A number of studies in our review adhere to conversation analysis (CA), an ethnomethodologically grounded approach to the study of the organization of social interaction (Sacks, Schegloff & Jefferson, 1974; Sidnell & Stivers, 2013) . From a CA perspective, BIB004 argues that OPIs constitute a particular variety of interaction different from, for example, L2 classroom interaction. Basing his analysis on data from the IELTS Speaking Test (IST, see also BIB003 ), Seedhouse compares patterns of turn-taking, repair, and the relationship between institutional goals and participant orientations in L2 classrooms and university interactions and shows that patterns of repair differ significantly between the OPIs and the other two settings (cf. also  . Aside from the strict turn allocation system and interactional asymmetry (candidateexaminer), the high demands on standardization only allows for particular forms of repair initiated by the examiner. Moreover, a striking feature of the IST is that there is 'no requirement to achieve intersubjectivity', that is, shared understanding based on negotiation of the meaning of turns and actions (Seedhouse 2013: 211) , as would be the case in other interactional varieties. Among other things, Seedhouse argues that findings from his study may inform test construction and rating scales. In a similar study, van Compernolle (2011) examined LPIs between a teacher and L2 French learners, focusing on precision timing and the conditional relevance of responses to questions, repairs, and nonunderstanding of questions. The sequential pattern of LPI talk identified was much like classroom interaction (teacher's question, student's response, and teacher's closing third turn, such as 'okay'). It is argued that responses to LPI questions index the learner's interactional competence as interviewees and that the preference of organization for providing a response overrides the appropriateness of the content of the response. The specific interactional competence that students can demonstrate relates to their 'socially constructed knowledge of what it means to interact with an LPI interviewer' and the 'rhetorical script' of the interview being enacted (p. 132), an observation that causes van Compernolle to join in existing critique of the interview format for assessing L2 OP.