Fix report text duplication for brms models

tests/testthat/test-brmsfit-duplication-fix.R

@@ -0,0 +1,65 @@
+test_that("brmsfit report_text method prevents duplication", {
+  skip_if_not_installed("brms")
+
+  # Test that the report_text.brmsfit method exists and is properly registered
+  expect_true("report_text.brmsfit" %in% methods("report_text"))
+
+  # If brms is available, test the actual functionality
+  if (requireNamespace("brms", quietly = TRUE)) {
+    skip_if_not_installed("rstan", "2.26.0")
+
+    # Create a simple brms model for testing
+    set.seed(333)
+    model <- suppressMessages(suppressWarnings(brms::brm(
+      mpg ~ wt,
+      data = mtcars, 
+      refresh = 0, 
+      iter = 200, 
+      chains = 1,
+      seed = 333
+    )))
+
+    # Test that report_text works without errors
+    text_result <- report_text(model)
+    expect_s3_class(text_result, "report_text")
+
+    # Test that the text content is reasonable (not empty, not duplicated)
+    text_content <- as.character(text_result)
+    expect_true(length(text_content) == 1)
+    expect_true(nchar(text_content) > 100)  # Should have substantial content
+
+    # Test that full report works without duplication
+    full_report <- report(model)
+    expect_s3_class(full_report, "report")
+
+    # Verify the text doesn't contain obvious duplication patterns
+    full_text <- as.character(full_report)
+    text_lines <- strsplit(full_text, "\n")[[1]]
+
+    # Check that we don't have identical consecutive lines (which would indicate duplication)
+    consecutive_identical <- FALSE
+    for (i in 1:(length(text_lines) - 1)) {
+      if (text_lines[i] == text_lines[i + 1] && nchar(text_lines[i]) > 10) {
+        consecutive_identical <- TRUE
+        break
+      }
+    }
+    expect_false(consecutive_identical, "Report text contains consecutive identical lines")
+  }
+})
+
+test_that("brmsfit report_text method maintains backward compatibility", {
+  # Test that the new method doesn't break when called on non-brms objects
+  # (in case of method dispatch issues)
+
+  model_lm <- lm(mpg ~ wt + hp, data = mtcars)
+
+  # This should still work with regular lm models
+  text_result <- report_text(model_lm)
+  expect_s3_class(text_result, "report_text")
+
+  # Verify that lm functionality is unchanged
+  text_content <- as.character(text_result)
+  expect_true(grepl("linear model", text_content))
+  expect_true(grepl("Within this model:", text_content))
+})