[MLv2] [Testing plan] Custom columns

[ranquild]

availableMetrics:

• returns a list of metrics for the source table
• returns an empty list when there are no metrics for the source table
• does not return metrics for other tables not used in the query
• does not return metrics for tables used in joins
• does not return metrics for stages other than 0
• does not return metrics for queries based on saved questions, both mbql and native

availableSegments:

• same as availableMetrics

legacyRef:

• works for columns
• works for segments -> ["segment", 1]
• works for metrics => ["metric", 1]

expressionClauseForLegacyExpression:

• works for simple expressions 1 + 2
• works for expressions with columns (with legacyRef)
• works for expressions with segments (with legacyRef)
• works for expressions with metrics (with legacyRef)
• result expression can be used to create a filter with filter call
• result expression can be used to create an aggregation with aggregate call
• result expression can be used to create a custom column with expression call

legacyExpressionForExpressionClause:

• works for simple expressions 1 + 2
• works for expressions with columns
• works for expressions with segments
• works for expressions with metrics
• works for filters obtained from filters call
• works for aggregations obtained from aggregations call
• works for custom columns obtained from expressions call
• works with expressionClauseForLegacyExpression - should result in the original expression

withExpressionName:

• works for filters obtained from filters call
• works for aggregations obtained from aggregations call
• works for custom columns obtained from expressions call
• works for expressions obtained from expressionClauseForLegacyExpression call
• allows to add the name for an expression without one and displayInfo uses this name
• allows to update the name for an expression and displayInfo uses this name

expression

• adds a new expression obtained from expressionClauseForLegacyExpression call

expressions

• returns expressions added with expression call