feat(context): Support loading import variables from absolute paths

This lets users specify the paths from which to import additional
variables using absolute paths in addition to relative paths.

This enables both loading of configuration files placed outside of the
resource set folder (if desired), as well as special use-cases such as
specifying `/dev/stdin` as an input path to read variables from
standard input.

This change supersedes #131

2 files changed, 20 insertions, 11 deletions

diff --git a/context/context.go b/context/context.go
index 42ad2e8c18..237d51435e 100644
--- a/context/context.go
+++ b/context/context.go
@@ -65,7 +65,7 @@ func contextLoadingError(filename string, cause error) error {
 // Attempt to load and deserialise a Context from the specified file.
 func LoadContext(filename string, explicitVars *[]string) (*Context, error) {
 	var ctx Context
-	err := util.LoadJsonOrYaml(filename, &ctx)
+	err := util.LoadData(filename, &ctx)
 
 	if err != nil {
 		return nil, contextLoadingError(filename, err)
@@ -105,8 +105,17 @@ func (ctx *Context) loadImportedVariables() (map[string]interface{}, error) {
 	allImportedVars := make(map[string]interface{})
 
 	for _, file := range ctx.VariableImportFiles {
+		// Ensure that the filename is not merged with the baseDir if
+		// it is set to an absolute path.
+		var filePath string
+		if path.IsAbs(file) {
+			filePath = file
+		} else {
+			filePath = path.Join(ctx.BaseDir, file)
+		}
+
 		var importedVars map[string]interface{}
-		err := util.LoadJsonOrYaml(path.Join(ctx.BaseDir, file), &importedVars)
+		err := util.LoadData(filePath, &importedVars)
 
 		if err != nil {
 			return nil, err
@@ -176,7 +185,7 @@ func loadDefaultValues(rs *ResourceSet, c *Context) *map[string]interface{} {
 	var defaultVars map[string]interface{}
 
 	for _, filename := range util.DefaultFilenames {
-		err := util.LoadJsonOrYaml(path.Join(c.BaseDir, rs.Path, filename), &defaultVars)
+		err := util.LoadData(path.Join(c.BaseDir, rs.Path, filename), &defaultVars)
 		if err == nil {
 			return util.Merge(&defaultVars, &rs.Values)
 		}
diff --git a/context/context_test.go b/context/context_test.go
index 6a4cec6c93..0af9dfc1c2 100644
--- a/context/context_test.go
+++ b/context/context_test.go
@@ -43,7 +43,7 @@ func TestLoadFlatContextFromFile(t *testing.T) {
 				Parent:  "",
 			},
 		},
-		BaseDir: "testdata",
+		BaseDir:      "testdata",
 		ImportedVars: make(map[string]interface{}, 0),
 		ExplicitVars: make(map[string]interface{}, 0),
 	}
@@ -84,14 +84,14 @@ func TestLoadContextWithResourceSetCollections(t *testing.T) {
 				Name: "collection/nested",
 				Path: "collection/nested",
 				Values: map[string]interface{}{
-					"lizards": "good",
+					"lizards":   "good",
 					"globalVar": "lizards",
 				},
 				Include: nil,
 				Parent:  "collection",
 			},
 		},
-		BaseDir: "testdata",
+		BaseDir:      "testdata",
 		ImportedVars: make(map[string]interface{}, 0),
 		ExplicitVars: make(map[string]interface{}, 0),
 	}
@@ -125,7 +125,7 @@ func TestSubresourceVariableInheritance(t *testing.T) {
 				Parent:  "parent",
 			},
 		},
-		BaseDir: "testdata",
+		BaseDir:      "testdata",
 		ImportedVars: make(map[string]interface{}, 0),
 		ExplicitVars: make(map[string]interface{}, 0),
 	}
@@ -157,7 +157,7 @@ func TestSubresourceVariableInheritanceOverride(t *testing.T) {
 				Parent:  "parent",
 			},
 		},
-		BaseDir: "testdata",
+		BaseDir:      "testdata",
 		ImportedVars: make(map[string]interface{}, 0),
 		ExplicitVars: make(map[string]interface{}, 0),
 	}
@@ -221,7 +221,7 @@ func TestValuesOverride(t *testing.T) {
 			"artist": "Pallida",
 			"track":  "Tractor Beam",
 		},
-		"place": "Oslo",
+		"place":     "Oslo",
 		"globalVar": "very global!",
 	}
 
@@ -260,7 +260,7 @@ func TestExplicitPathLoading(t *testing.T) {
 				Parent:  "",
 			},
 		},
-		BaseDir: "testdata",
+		BaseDir:      "testdata",
 		ImportedVars: make(map[string]interface{}, 0),
 		ExplicitVars: make(map[string]interface{}, 0),
 	}
@@ -288,7 +288,7 @@ func TestExplicitSubresourcePathLoading(t *testing.T) {
 				Values: make(map[string]interface{}, 0),
 			},
 		},
-		BaseDir: "testdata",
+		BaseDir:      "testdata",
 		ImportedVars: make(map[string]interface{}, 0),
 		ExplicitVars: make(map[string]interface{}, 0),
 	}