acc: Write out.requests.txt immediately (#2368)

## Changes
- Instead of collecting requests in memory and writing them at the end
of the test, write them right away. Then test authors can do filtering
with jq in 'script' or collect individual files per different command.
- testserver is now simpler - it just calls a caller-provided function.
The logging logic is moved to acceptance_test.go.

See https://github.com/databricks/cli/pull/2359/files#r1967591173

## Tests
Existing tests.

acceptance/acceptance_test.go

@@ -7,6 +7,7 @@ import (
 	"flag"
 	"fmt"
 	"io"
+	"net/http"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -27,6 +28,7 @@ import (
 	"github.com/databricks/cli/libs/testserver"
 	"github.com/databricks/databricks-sdk-go"
 	"github.com/databricks/databricks-sdk-go/service/iam"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
@@ -263,8 +265,23 @@ func runTest(t *testing.T, dir, coverDir string, repls testdiff.ReplacementsCont
 
 		if len(config.Server) > 0 || config.RecordRequests {
 			server = testserver.New(t)
-			server.RecordRequests = config.RecordRequests
-			server.IncludeRequestHeaders = config.IncludeRequestHeaders
+			if config.RecordRequests {
+				requestsPath := filepath.Join(tmpDir, "out.requests.txt")
+				server.RecordRequestsCallback = func(request *testserver.Request) {
+					req := getLoggedRequest(request, config.IncludeRequestHeaders)
+					reqJson, err := json.MarshalIndent(req, "", "  ")
+					assert.NoErrorf(t, err, "Failed to indent: %#v", req)
+
+					reqJsonWithRepls := repls.Replace(string(reqJson))
+
+					f, err := os.OpenFile(requestsPath, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0o644)
+					assert.NoError(t, err)
+					defer f.Close()
+
+					_, err = f.WriteString(reqJsonWithRepls + "\n")
+					assert.NoError(t, err)
+				}
+			}
 
 			// We want later stubs takes precedence, because then leaf configs take precedence over parent directory configs
 			// In gorilla/mux earlier handlers take precedence, so we need to reverse the order
@@ -345,25 +362,6 @@ func runTest(t *testing.T, dir, coverDir string, repls testdiff.ReplacementsCont
 	cmd.Dir = tmpDir
 	err = cmd.Run()
 
-	// Write the requests made to the server to a output file if the test is
-	// configured to record requests.
-	if config.RecordRequests {
-		f, err := os.OpenFile(filepath.Join(tmpDir, "out.requests.txt"), os.O_CREATE|os.O_WRONLY, 0o644)
-		require.NoError(t, err)
-
-		for _, req := range server.Requests {
-			reqJson, err := json.MarshalIndent(req, "", "  ")
-			require.NoErrorf(t, err, "Failed to indent: %#v", req)
-
-			reqJsonWithRepls := repls.Replace(string(reqJson))
-			_, err = f.WriteString(reqJsonWithRepls + "\n")
-			require.NoError(t, err)
-		}
-
-		err = f.Close()
-		require.NoError(t, err)
-	}
-
 	// Include exit code in output (if non-zero)
 	formatOutput(out, err)
 	require.NoError(t, out.Close())
@@ -670,3 +668,38 @@ func RunCommand(t *testing.T, args []string, dir string) {
 		t.Logf("%s output: %s", args, out)
 	}
 }
+
+type LoggedRequest struct {
+	Headers http.Header `json:"headers,omitempty"`
+	Method  string      `json:"method"`
+	Path    string      `json:"path"`
+	Body    any         `json:"body,omitempty"`
+	RawBody string      `json:"raw_body,omitempty"`
+}
+
+func getLoggedRequest(req *testserver.Request, includedHeaders []string) LoggedRequest {
+	result := LoggedRequest{
+		Method:  req.Method,
+		Path:    req.URL.Path,
+		Headers: filterHeaders(req.Headers, includedHeaders),
+	}
+
+	if json.Valid(req.Body) {
+		result.Body = json.RawMessage(req.Body)
+	} else {
+		result.RawBody = string(req.Body)
+	}
+
+	return result
+}
+
+func filterHeaders(h http.Header, includedHeaders []string) http.Header {
+	headers := make(http.Header)
+	for k, v := range h {
+		if !slices.Contains(includedHeaders, k) {
+			continue
+		}
+		headers[k] = v
+	}
+	return headers
+}

libs/testserver/server.go

@@ -7,7 +7,6 @@ import (
 	"net/http/httptest"
 	"net/url"
 	"reflect"
-	"slices"
 	"strings"
 	"sync"
 
@@ -26,18 +25,7 @@ type Server struct {
 	fakeWorkspaces map[string]*FakeWorkspace
 	mu             *sync.Mutex
 
-	RecordRequests        bool
-	IncludeRequestHeaders []string
-
-	Requests []LoggedRequest
-}
-
-type LoggedRequest struct {
-	Headers http.Header `json:"headers,omitempty"`
-	Method  string      `json:"method"`
-	Path    string      `json:"path"`
-	Body    any         `json:"body,omitempty"`
-	RawBody string      `json:"raw_body,omitempty"`
+	RecordRequestsCallback func(request *Request)
 }
 
 type Request struct {
@@ -265,10 +253,9 @@ func (s *Server) Handle(method, path string, handler HandlerFunc) {
 		}
 
 		request := NewRequest(s.t, r, fakeWorkspace)
-		if s.RecordRequests {
-			s.Requests = append(s.Requests, getLoggedRequest(request, s.IncludeRequestHeaders))
+		if s.RecordRequestsCallback != nil {
+			s.RecordRequestsCallback(&request)
 		}
-
 		respAny := handler(request)
 		resp := normalizeResponse(s.t, respAny)
 
@@ -296,33 +283,6 @@ func getToken(r *http.Request) string {
 	return header[len(prefix):]
 }
 
-func getLoggedRequest(req Request, includedHeaders []string) LoggedRequest {
-	result := LoggedRequest{
-		Method:  req.Method,
-		Path:    req.URL.Path,
-		Headers: filterHeaders(req.Headers, includedHeaders),
-	}
-
-	if json.Valid(req.Body) {
-		result.Body = json.RawMessage(req.Body)
-	} else {
-		result.RawBody = string(req.Body)
-	}
-
-	return result
-}
-
-func filterHeaders(h http.Header, includedHeaders []string) http.Header {
-	headers := make(http.Header)
-	for k, v := range h {
-		if !slices.Contains(includedHeaders, k) {
-			continue
-		}
-		headers[k] = v
-	}
-	return headers
-}
-
 func isNil(i any) bool {
 	if i == nil {
 		return true