
library(testthat)

source("user_code.R")
test_that("attach_metadata attaches meta as custom_metadata attribute", {
  df <- data.frame(a = 1:3, b = c("x", "y", "z"))
  meta <- list(source = "survey", created = "2024-06-01", notes = "Sample data for EDA")
  df_with_meta <- attach_metadata(df, meta)
  expect_true(!is.null(attr(df_with_meta, "custom_metadata")),
              info = "custom_metadata attribute should not be NULL after attaching metadata")
  expect_equal(attr(df_with_meta, "custom_metadata"), meta,
               info = "custom_metadata attribute does not match original meta list")
})

test_that("attach_metadata returns the data frame with metadata", {
  df <- data.frame(a = 1:3, b = c("x", "y", "z"))
  meta <- list(source = "survey", created = "2024-06-01", notes = "Sample data for EDA")
  df_with_meta <- attach_metadata(df, meta)
  expect_true(is.data.frame(df_with_meta),
              info = "Returned object must be a data frame")
  expect_equal(df_with_meta$a, df$a,
               info = "Column 'a' values must match original data frame")
  expect_equal(df_with_meta$b, df$b,
               info = "Column 'b' values must match original data frame")
})

test_that("get_metadata retrieves custom_metadata attribute correctly", {
  df <- data.frame(a = 1:3, b = c("x", "y", "z"))
  meta <- list(source = "survey", created = "2024-06-01", notes = "Sample data for EDA")
  df_with_meta <- attach_metadata(df, meta)
  retrieved_meta <- get_metadata(df_with_meta)
  expect_equal(retrieved_meta, meta,
               info = "Retrieved metadata does not match the original meta list")
})

test_main.R

Master the essential R data structures used in exploratory data analysis (EDA), focusing on practical applications and hands-on challenges. This course is designed for learners already familiar with R syntax, core data structures, and data cleaning/wrangling techniques.

Explore the essential R data structures that power effective exploratory data analysis, with a focus on practical usage and hands-on challenges.

Challenge: Metadata

Solution